* cleanup build system, modernize cmake
* build glfw and sdl2, w/ or w/o freetype
* fix android demo build
* win32 with CPack has PACKAGE target now
* added GLEW for windows
* bump to SDL2.0.10. fixes for building as subdir
* constexpr is always available these days.
* cleanup getwd() warning. add rpm to ubuntu packages
* dont use add_compile_definitions() for cmake, too new
* add rpm package to travis
* gh release packages
* build demo target on windows
* see if defines not working on winsodw
