Clean up of project's auto-generated header file version.[cpp|hpp].in

* CMakeLists.txt: Remove auto-generation of version.cpp.in file.
* src/CMakeLists.txt: Remove auto-generated 'version.cpp' file from
sources.
* Rename include/nomlib/config.hpp to cmake/templates/config.hpp.in --
include/nomlib/config.hpp is now an auto-generated cmake file, and
therefore has also been removed from the repository's file cache.
* cmake/templates/version.hpp.in: Remove vars PLATFORM_ARCH_64_BIT,
NOMLIB_INSTALL_PREFIX && NOMLIB_BUNDLE_IDENTIFIER. (These variables
are not used, nor necessary!)
* cmake/templates/version.hpp.in: Relocate <string> header file
inclusion to types.hpp && cmake define NOM_USE_SDL2_ASSERT to
cmake/templates/config.hpp.in.

* types.hpp: Simplify the type definition of 'ulong', including the
static assert checks.

* SpriteSheet: Remove inclusion of nomlib/version.hpp header file; not
necessary as we already included nomlib/config.hpp.

* .gitignore: Remove version.cpp & add config.hpp to ignore filter.