ZVISION: Make the rest of the controls properly use VideoDecoder timing

The hacky use of getDuration() to retrieve the framerate() is gone

Thanks to md5 for testing (and for filling in a few gaps since I was coding in the blind ;))
CREDITS: Update credits for ZVision again
ZVISION: Show system messages when subtitles are disabled

Thanks to Marisa-Chan for spotting this
GUI: Do not overwrite write protected saves in grid based save dialog.

This fixes overwriting of, for example, autosaves in the grid based save load
dialog when using "New Save".
ZVISION: Fix font error message condition
ZVISION: Search fonts in game directory (e.g. in game/FONTS/)
ZVISION: Further cleanup to the AnimationNode class
ZVISION: Initialize the starting frame to -1 in RLF animations
ZVISION: White space
Revert "ZVISION: Further cleanup to the AnimationNode class"

This reverts commit 0c4e0673c3a7d17aef7c586251c3990104163bc3.

Conflicts:
	engines/zvision/scripting/sidefx/animation_node.cpp
ZVISION: Make RLF curFrame like in AVI decoder
Merge branch 'master' of https://github.com/Marisa-Chan/scummvm

Conflicts:
	engines/zvision/text/truetype_font.cpp
	engines/zvision/zvision.cpp