Revert "Use spine instead of shoulders to determine vertical gun pitch."

This reverts commit a04bd869c11bfbc31b378fa96d4ebee6fb17108a.
pre-cherry-pick some parts of b044e0a to simplify future mergings -- it introduces g_debugEntities, but without any logic attached to it
Merge branch 'master' into entities

Conflicts:
	src/gamelogic/game/g_main.c