Cubemap Erweitert

Signed-off-by: Philipp Liepert <philipp@phillsoft.de>
Merge branch 'master' of https://github.com/real-time-rendering/webgl-a1

Signed-off-by: Philipp Liepert <philipp@phillsoft.de>

Conflicts:
	lesson04/uebung5/uebung5.js
bla

Signed-off-by: Philipp Liepert <philipp@phillsoft.de>
Merge branch 'master' of https://github.com/real-time-rendering/webgl-a1
Bla

Signed-off-by: Philipp Liepert <philipp@phillsoft.de>