Change how default compiler options are set for CMake build
Change how default compiler options are set for CMake build

No longer set CMAKE_BUILD_TYPE to RelWithDebInfo by default
Automatically set CMAKE_C_FLAGS to '-O2 -g', but only if the compiler is not MVC and neither CMAKE_BUILD_TYPE and CMAKE_C_FLAGS have been explicitly set by the user.

stcorp/harp,stcorp/harp,stcorp/harp,stcorp/harp,stcorp/harp,stcorp/harp