Adding info functions to proj.h API. (#551)

* Adding info functions to proj.h API.

Four new functions are added with this commit: proj_info(), proj_pj_info(),
proj_grid_info() and proj_init_info(). Additionally four new data types are
added: PJ_INFO, PJ_PROJ_INFO, PJ_GRID_INFO and PJ_INIT_INFO. The functions
return the corresponding data types.

These functions allows users of the PROJ.4 library to get information about
various PROJ.4 entities and the library itself. The new data types are structs
that contain specific information about either the library instance, a PJ
instance, a grid or an init file. Together the four new functions cover a big
part of the functionality in the semi-public projects.h API and should hopefully
make it easier for user to migrate their code to the proj.h API in the future.

Besides covering already existing functionality in the old API, this commit
introduces the ability to add metadata to init-files. This is primarily added
to give users a way of knowing which version of the EPSG database they are
using, but it also comes in handy for other init-files. The init-file metadata
is added directly to the init-file as a special "projection" called "metadata".
The info projection of the epsg init-file is thus described as:

    <metadata> +version=9.0.0 +origin=EPSG +lastupdate=2017-01-10

The proj_init_info() function uses the internal pj_param() to read the
metadata. As a consequence, "metadata" will not be available as a the name of
a projection in the future. This is a reasonable price to pay considering the
ease of the implementation of adding metadata to init-files this way, and of
course that "metadata" is a very unlikely name for a projection in any case.
A metadata tag has been added to all init-files in the nad-directory. For most
only a subset of the possible parameters has been added.

* Replaced calls to sprintf and strncpy with safer options. Added pj_strlcpy for internal use.

* Fail gracefully when getting non-initialized PJ in proj_pj_info()

* Change length of filename member in PJ_INIT_INFO and PJ_GRID_INFO to 260 (MAX_PATH)

0 files changed, 0 insertions, 0 deletions