Fixes #1001

Co-authored-by: Chris Crook <ccrook@linz.govt.nz>

* Use instead of CMAKE_SOURCE_DIR and CMAKE_BINARY_DIR
* Also PROJECT_SOURCE_DIR and PROJECT_BINARY_DIR, which are similar
* Set properties with a list variable rather than a long line
* Correction to 'proj_test_set_properties' function, rename ENVIRONMENT:
  - PROJ_IGNORE_USER_WRITABLE_DIRECTORY     (ignored)
  - PROJ_SKIP_READ_USER_WRITABLE_DIRECTORY  (used by filemanager.cpp)

CMake: rename BUILD_LIBPROJ_SHARED to BUILD_SHARED_LIBS

* Autotools interface should be the same, but different ./configure --help
* For CMake, the option should be -DENABLE_TIFF=NO (default is YES)
* Use TIFF_ENABLED and CURL_ENABLED variables, based on option and outcome
* Reword some messages and add hints
* Move -DTIFF_ENABLED and -DCURL_ENABLED from global add_definitions()
  to target_compile_definitions(), which is recommended practice
* Minor spelling and style consistency around SQLITE_VERSION check

* Deprecate BUILD_LIBPROJ_SHARED, but still use it as an alias for now
* Rename BUILD_LIBPROJ_SHARED_DEFAULT to BUILD_SHARED_LIBS_DEFAULT
* Keep previous defaults (UNIX as shared and Windows as static)
* Remove PROJ_LIBRARY_TYPE, since add_library() uses BUILD_SHARED_LIBS

This commit is the result of the squashing of rfc4_dev branch in a single
commit. It implements mostly RFC 4 related work.

* Grid handling:
  - remove obsolete and presumably unfinished implementation of grid catalog functionality
  - all grid functionality is in grids.cpp/.hpp
  - vertical and horizontal grid shift: rework to no longer load whole grid into memory
  - remove hgrids and vgrids member from PJ structure, and store them in hgridshift/vgridshift/deformation structures
  - build systems: add optional libtiff dependency. Must be explicitly disabled if not desired
  - add support for horizontal and vertical grids in GeoTIFF, if libtiff is available
  - add GenericShiftGridSet and GenericShiftGrid classes, relying on TIFF grids, that can be used for generic purpose grid-based adjustment
  - add a +proj=xyzgridshift method to perform geocentric translation by grid. Used for French NTF to RGF93 transformation using gr3df97a.tif grid
  - deformation: add support for +grids= for GeoTIFF grids
  - horizontal grid shift: fix failures on points slightly outside a subgrid (fixes #209)

* File management:
  - add a filemanager.cpp/.hpp to deal with file related work
  - test for legacy proj_api.h fileapi
  - proj.h: add proj_context_set_fileapi() and proj_context_set_sqlite3_vfs_name() (fixes #866)
  - add capability to read resource files from the user writable directory

* Network access:
  - build systems: add optional curl dependency
  - add a curl-based default implementation for network related functionality
  - proj.h: add C API to control network functionality, and optionaly provide network callbacks
  - add data/proj.ini with default settings
  - add a SQLite3 local cache of downloaded chunks
  - add proj_is_download_needed() and proj_download_file()

* Use Win32 Unicode APIs and expect all strings to be UTF-8 (fixes #1765)
  For backward compatibility, if PROJ_LIB content is found to be not UTF-8 or
  pointing to a non existing directory, then an attempt at interpretating it
  in the ANSI page encoding is done.
  proj_context_set_search_paths() now assumes strings to be in UTF-8, and
  functions returning paths will also return values in UTF-8.

Remove (most) needs to fiddle with CMAKE_C_FLAGS / CMAKE_CXX_FLAGS

HAVE_STRERROR is defined in proj_config.h.