Add (optional) confirmation dialog on exit
Fix #179 (Crash on exit)
Use inverse scale for UDMF floor/wall scale properties

Fixes #177
Center the texture editor patch browser by default
Correct invalid lines created via line drawing anti-clockwise

Fixes #181
Uncheck textures from base resource by default in 'Remove Unused Textures' function

Close #174
Flip line if second side sector is set with no first side on create sector (#181)
Add SLADE 2 colour configuration
Rename default.txt to Default.txt
Bump version to 3.1.0.1
Merge branch 'master'
Initial work on generic data entry panel, opens only basic map data entries so far
More work on DataEntryPanel

- Support more formats
- Ability to add/delete/cut/copy/paste rows