Added option COPY_CONFIG_ON_BUILD, if set to OFF then post-process
command that copies config & mods directories to build destination will
be disabled.
This command may be convenient in most cases, but when only config file is
edited CMake won't trigger this command since lib was not changed.
At least on Linux, symlinks are more reliable alternative
- the moved CMakeLists.txt is turned into a macro (adds whitespace difference)
- now uses absolute paths to the lib and include dirs
- refactors iOS install section to use "early continue" in the foreach loop
