- added gravity property to UDMF things. Positive values are multiplied with the class's gravity property, negative values are used as their absolute.
- added MF5_NOFORWARDFALL flag to prevent attacks from making its victim fall forward randomly.
- added ML_BLOCKHITSCAN line flag.
Merge branch 'maint'
- fixed: When creating colormaps for 3D floors the model sector's fade value must be used when defining a fog volume.
- added MF6_NOTONAUTOMAP flag to exclude things from being shown with the scanner powerup. The IDDT cheat will not be affected by this.
- added MF6_RELATIVETOFLOOR flag.
Merge branch 'maint'

Conflicts:
	src/am_map.cpp
- let APowerRegeneration use the Strength property to define the amount of regeneration it gives.
Merge branch 'maint'
- fixed typo in Strife spectre's obituary message and added it to the DECORATE definition of the spectre.
- specte typo in language.ptb.
Merge branch 'maint'
- fixed bad index variable in R_RenderFakeWallRange.
- removed obsolete quit message #defines.
Merge branch 'maint'
- fixed: Powerup.Strength is a fixed point value, so using it as health amount for PowerRegeneration requires division by FRACUNIT.
- Added A_DropItem for DECORATE.
- DropItem for ACS.
Merge branch 'maint'