Add section on PROJ resource files to docs [skip ci]

Added new section on PROJ resource files to the top level of the
documentation. Moved information on init-file from the 'usage'
chapter to the new section. Also moved pages on grids and HTPD to the
new resource files section. Finally links and information on the new
regional datumgrids packages is added.

2 files changed, 0 insertions, 122 deletions

diff --git a/docs/source/usage/index.rst b/docs/source/usage/index.rst
index d59296d0..c581fd03 100644
--- a/docs/source/usage/index.rst
+++ b/docs/source/usage/index.rst
@@ -16,7 +16,6 @@ command line applications or the C API that is a part of the software package.
    apps/index
    projections
    transformation
-   resource_files
    environmentvars
    operations/index
 
diff --git a/docs/source/usage/resource_files.rst b/docs/source/usage/resource_files.rst
deleted file mode 100644
index 7a1dea8b..00000000
--- a/docs/source/usage/resource_files.rst
+++ /dev/null
@@ -1,121 +0,0 @@
-.. _resource_files:
-
-================================================================================
-Resource files
-================================================================================
-
-A number of files containing preconfigured transformations and default parameters
-for certain projections are bundled with the PROJ distribution. Init files
-contains preconfigured proj-strings for various coordinate reference systems
-and the defaults file contains default values for parameters of select
-projections.
-
-Init files
--------------------------------------------------------------------------------
-
-Init files are used for preconfiguring proj-strings for often used
-transformations, such as those found in the EPSG database. Most init files contain
-transformations from a given coordinate reference system to WGS84. This makes
-it easy to transformations between any two coordinate reference systems with
-``cs2cs``. Init files can however contain any proj-string and don't necesarily
-have to follow the *cs2cs* paradigm where WGS84 is used as a pivot datum. The
-ITRF init file is a good example of that.
-
-A number of init files come pre-bundled with PROJ but it is also possible to
-add your own custom init files. PROJ looks for the init files in the directoty
-listed in the ``PROJ_LIB`` environment variable.
-
-The format of init files made up of a identifier in angled brackets and a
-proj-string:
-
-::
-
-    <3819> +proj=longlat +ellps=bessel
-           +towgs84=595.48,121.69,515.35,4.115,-2.9383,0.853,-3.408 +no_defs <>
-
-The above example is the first entry from the ``epsg`` init file. So, this is the
-coordinate reference system with ID 3819 in the EPSG database. Comments can be
-inserted by prefixing them with a "#". With version 4.10.0 a new special metadata
-entry is now accepted in init files. It can be parsed with a function from the public
-API. The metadata entry in the epsg init file looks like this at the time of writing:
-
-::
-
-<metadata> +version=9.0.0 +origin=EPSG +lastupdate=2017-01-10
-
-Pre-configured proj-strings from init files are used in the following way:
-
-::
-
-    $ cs2cs -v +proj=latlong +to +init=epsg:3819
-    # ---- From Coordinate System ----
-    #Lat/long (Geodetic alias)
-    #
-    # +proj=latlong +ellps=WGS84
-    # ---- To Coordinate System ----
-    #Lat/long (Geodetic alias)
-    #
-    # +init=epsg:3819 +proj=longlat +ellps=bessel
-    # +towgs84=595.48,121.69,515.35,4.115,-2.9383,0.853,-3.408 +no_defs
-
-It is possible to override parameters when using ``+init``. Just add the parameter
-to the proj-string alongside the ``+init`` parameter. For instance by overriding
-the ellipsoid as in the following example
-
-::
-
-    +init=epsg:25832 +ellps=intl
-
-where the Hayford ellipsoid is used instead of the predefined GRS80 ellipsoid.
-It is also possible to add additional parameters not specified in the init file,
-for instance by adding an obervation epoch when transforming from ITRF2000 to
-ITRF2005:
-
-::
-
-    +init=ITRF2000:ITRF2005 +tobs=2010.5
-
-which then expands to
-
-::
-
-    +proj=helmert +x=-0.0001 +y=0.0008 +z=0.0058 +s=-0.0004
-    +dx=0.0002 +dy=-0.0001 +dz=0.0018 +ds=-0.000008
-    +epoch=2000.0 +transpose
-    +tobs=2010.5
-
-Below is a list of the init files that are packaged with PROJ.
-
-    ========    ================================================================
-    Name        Description
-    ========    ================================================================
-    esri        Auto-generated mapping from Esri projection index. Not
-                maintained any more
-    epsg        EPSG database
-    GL27        Great Lakes Grids
-    IGNF        French coordinate systems supplied by the IGNF
-    ITRF2000    Full set of transformation parameters between ITRF2000 and other
-                ITRF's
-    ITRF2008    Full set of transformation parameters between ITRF2008 and other
-                ITRF's
-    ITRF2014    Full set of transformation parameters between ITRF2014 and other
-                ITRF's
-    nad27       State plane coordinate systems, North American Datum 1927
-    nad83       State plane coordinate systems, North American Datum 1983
-    ========    ================================================================
-
-
-Defaults file
--------------------------------------------------------------------------------
-
-The ``proj_def.dat`` file supplies default parameters for PROJ. It uses the same
-syntax as the init files described above. The identifiers in the defaults file
-describe to what the parameters should apply. If the ``<general>`` identifier is
-used, then all parameters in that section applies for all proj-strings. Otherwise
-the identifier is connected to a specific projection. With the defaults file
-supplied with PROJ the default ellipsoid is set to WGS84 (for all proj-strings).
-Apart from that only the Albers Equal Area,
-:doc:`Lambert Conic Conformal<operations/projections/lcc>` and the
-:doc:`Lagrange<operations/projections/lagrng>` projections have default parameters.
-Defaults can be ignored by adding the ``+no_def`` parameter to a proj-string.
-