Convert old frame flags in Metal recordings to their 2.2.10 equivalents

This branch increments DEMOVERSION, and converts Metal's frame flags in older demos to their 2.2.10 equivalents, since !1656 (merged) move some of their values around. Fixes #775 (closed), which was caused by FF_VERTICALFLIP now having the value of FF_ANIMATE.

srb2win_demoframeflags.exe based on next, beware save files etc.

changed milestone to %2.2.10

added Bug Regression labels

merged

mentioned in commit 0ad2ac68