Merge RFC4 (#1865)

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.

1 files changed, 21 insertions, 0 deletions

diff --git a/test/unit/test_c_api.cpp b/test/unit/test_c_api.cpp
index a657c61e..5c6dabba 100644
--- a/test/unit/test_c_api.cpp
+++ b/test/unit/test_c_api.cpp
@@ -4467,6 +4467,27 @@ TEST_F(CApi, proj_create_derived_geographic_crs) {
 
 // ---------------------------------------------------------------------------
 
+TEST_F(CApi, proj_context_set_sqlite3_vfs_name) {
+
+    PJ_CONTEXT *ctx = proj_context_create();
+    proj_log_func(ctx, nullptr, [](void *, int, const char *) -> void {});
+
+    // Set a dummy VFS and check it is taken into account
+    // (failure to open proj.db)
+    proj_context_set_sqlite3_vfs_name(ctx, "dummy_vfs_name");
+    ASSERT_EQ(proj_create(ctx, "EPSG:4326"), nullptr);
+
+    // Restore default VFS
+    proj_context_set_sqlite3_vfs_name(ctx, nullptr);
+    PJ *crs_4326 = proj_create(ctx, "EPSG:4326");
+    ASSERT_NE(crs_4326, nullptr);
+    proj_destroy(crs_4326);
+
+    proj_context_destroy(ctx);
+}
+
+// ---------------------------------------------------------------------------
+
 TEST_F(CApi, proj_is_equivalent_to_with_ctx) {
     auto from_epsg = proj_create_from_database(m_ctxt, "EPSG", "7844",
                                                PJ_CATEGORY_CRS, false, nullptr);