Don't change function parameter types for Q_strncpyz in debug builds
Fix undefined totalWeight value crash.

Happens after the map is loaded.
cgame: change cgs.mapname to 'maps/_.bsp' to '_'
renderers: add ScissorSet and ScissorEnable

Used to control temporarily glScissor, the scissor is also modified
by other parts of the renderer.
Adapted from a commit from `Ishq (ded55d8f12e03aceff) + fixes
cgame: Add scissoring support
Merge branch 'master' into librocket

Conflicts:
	src/engine/client/cg_api.h
	src/engine/client/cl_cgame.c
	src/engine/renderer/tr_init.c
	src/engine/renderer/tr_local.h
	src/engine/rendererGL/tr_local.h
	src/gamelogic/cgame/cg_api.asm
	src/gamelogic/cgame/cg_api.c