Introduced PKMDS_CMAKE_USED macro

* If CMake is used, include paths will be <pkmds/pkmds_g5.h>, etc
* If not, include paths will be "PKMDS-G5\include\pkmds\pkmds_g5.h", etc
* Allows for builds with CMake or without
Merge pull request #9 from ncorgan/cmake_conditional

Introduced PKMDS_CMAKE_USED macro