WINTERMUTE: Fix typo in comment
BASE: Fix uninitialized type field in plugin base class. CID 1002938.
COMPOSER: Fix uninitialized class variables and divide by zero bugs.

This was highlighted by Coverity in CID 1003844 and 1003410.
GRAPHICS: Fix uninitialized cursor visibility variable. CID 1002283.

The default at cursor construction has been set to not visible.
This now requires an explicit call to setVisible(true) to show the
cursor, but a basic test shows that this seems to be OK and engines
which fail to do this would have been intermittently broken before.
GUI: Fix missing initializers for ListWidget. CID 1002259.
GRAPHICS: Fix uninitialised field in PNG decoder. CID 1002280.
WINTERMUTE: Remove almost unused _colorMod field

The one actual use of this left-over variable was a bug breaking at
least menu text color in Chivalry when dirty rects were disabled.
Merge branch 'master' into wme_rendering

Conflicts:
	engines/wintermute/base/gfx/osystem/base_render_osystem.cpp