SCUMM: Implement original AD AdLib output.

This implements the original AD output and enables it for Indy3 and Loom DOS.
It is not enabled for Monkey Island DOS because it would break multi MIDI
support. However, there are also drawbacks for Indy3. In the catacombs
we were able to play sfx (Indy walking around) and the background music
at once. This was not supported in the original player and thus also does
not work with this reimplementation.

This fixes bug #2027877 "INDY3: Non-Looping Sound Effects".
This fixes bug #1159581 "ADLIB: Adlib Emulation doesn't Respect Volume Settings"
for Indy3 and Loom.
GUI: Use Domain::const_iterator in EventRecorder code when possible.
COMMON: Do not let ConfigManager::Domain inherit from StringMap.

Instead we provide wrapper functionality now. Intuitively a Domain is not a
simple StringMap.
GRAPHICS: Fix VectorRendererSpec for RGBA8888.

Formerly values in the gradient and blending code overflowed and thus caused
incorrect colors. Now there's some special case for 32bpp modes, which needs
slightly more operations but assures a correct output.
GRAPHICS: Add error-checking in blendPixelPtr for invalid BPPs
GRAPHICS: Fix fonts/bdf.cpp to allow for 32bpp to be used
GUI: Allow GUI cursor creation to work with abitrary 2/4Bpp formats.
GUI: Change name of GUI-renderers to remove "16-bit"
GRAPHICS: Allow VectorRenderer and ThemeEngine to init with 4BPP
WINTERMUTE: Avoid setting alpha-image when filename is ""
WINTERMUTE: Fix uninitialized scalar field (CID1060922)
MORTEVIELLE: Use more accurate frequency for music
MORTEVIELLE: Play ambiant sounds
MORTEVIELLE: some refactoring in ambiant sound code
MORTEVIELLE: Handle sounds
TINSEL: Fix DW2 assertion when quitting during cutscene

Call _bmv->FinishBMV() before setting g_pCurBgnd to NULL. Otherwise,
there will be an assertion if quitting during a cutscene while a
subtitle is being shown. (At least I think that's the condition.)

(Also, it seems to be a good idea to call it before EndScene(),
because even though there was no assertion, I got a lot of warnings
when I did it after.)
Merge branch 'master' of github.com:scummvm/scummvm
MORTEVIELLE: Some refactoring in noise sound code
MORTEVIELLE: Avoid loading sfx and noise files multiple times
MORTEVIELLE: Fix check of end of stream