Merge branch 'master' of https://github.com/sirjuddington/SLADE into Music
Show metadata for extended modules
Update Square palettes
Make edit level script button more explicit
Partial revert to allow merging.
Tighter checks on TGA and Beta graphics

Fixes #214.
Fix sector type definitions.

- Sector types weren't being cleared when loading new configuration, so
  they "bled" from one map editing session to the next.

- When editing a ZDoom Hexen or UDMF map derived from Doom, the Doom
  sector types were listed, even though those sector types are only
  recognized for Doom-format maps.

- Several ZDoom sector types were misnumbered.

- Strife didn't have its own sector types list, but it uses slightly
  different ones from Doom.
Restore Boom-derived sector type flags to ZDoom.

They were disabled when Boom features were set to only be enabled in
Doom-format maps, but unlike some other Boom extensions, these still
work.  They're now their own configuration property, which also allowed
for removing a lot of special-casing by map format.

The sector special propgrid panel now also shows the name of the sector
special.
Merge pull request #215 from eevee/restore-sector-specials

Fix sector special definitions and restore flags under ZDoom.
Merge branch 'master' of https://github.com/sirjuddington/SLADE into Music