update branchAndTrack to detect python version
and use shell for subprocess
add premake to linux build requirements
add libsdl2 to build requirements
symlink assets into bin/
Merge branch 'master' of https://github.com/shearer12345/graphics_examples_in_git_branches
prevent from adding existing local branches
update existing local branches
add checkout master to start of branchAndTrack
install libsdl2-dev
add ppa sources for sdl2
Merge branch 'master' into sdlHelloWorld
make clearer about cloning and running premake on Windows
Merge branch 'master' into sdlHelloWorld