Revert "implemented add_subproject macro"

This reverts commit 05b0618fed185cc69b29af3c880fd72a6587d063.
updated
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Merge branch 'master' of https://github.com/UVicGameDevCPlusPlus/GLmesh into HEAD
Merge branch 'master' of https://github.com/UVicGameDevCPlusPlus/GLplus into HEAD
Merge branch 'master' of https://github.com/UVicGameDevCPlusPlus/glew into HEAD
Merge branch 'master' of https://github.com/UVicGameDevCPlusPlus/SDL2plus into HEAD
Merge branch 'master' of https://github.com/UVicGameDevCPlusPlus/soil2 into HEAD
Merge branch 'master' of https://github.com/UVicGameDevCPlusPlus/tinyobjloader into HEAD
fixed typo
Merge branch 'master' of https://github.com/UVicGameDevCPlusPlus/GLplus into HEAD
added subproject thing
removed dummy
Merge branch 'master' of https://github.com/UVicGameDevCPlusPlus/glm into HEAD
added include directories
Merge branch 'master' of https://github.com/UVicGameDevCPlusPlus/glm into HEAD