SDL/OPENGL: added info about GLSL version
EMI: Allow nil X, Y and Z values in SetActorHead.

This fixes Deadeye Dave's animation in pop.
EMI: If the head joint name is empty, don't do head tracing.
Merge pull request #962 from Akz-/emi-head-fixes

EMI: Fix Deadeye Dave's head
EMI: Implement screenshot thumbnails for savegames
GRAPHICS: Initialize/Destroy _storedDisplay
DEVTOOLS: it's not needed add non source code files into mdvc project
DEVTOOLS: disable build MT32 with msvc
DEVTOOLS: no need link with GLU32 in msvc
DEVTOOLS: define needs to be commented out if empty
ALL: synced with ScummVM
DEVTOOLS: disable flac and ogg/vorbis in msvc projects
OPENGL: remove GLU leftovers
BASE: correct to official description
ALL: unify setupScreen() arguments type
EMI: Free materials as soon as they are no longer in use by any costumes.
SDL: added safeguard for clearOverlay() if overlay is closed
SDL: don't call error() inside setupScreen(), it will crash if debugger is used
GRIM: Implement the getDebugger API

This allows errors to be shown in the debugger
EMI: Implement projection shadows.