Clean up check objects on m_check console command
Disabled update when map window is in background

Even with map_bg_ms CVAR set to 1000 map canvas updates consume significant amount of one CPU core cycles.
It’s important for mobile computers to reduce noise, heat and battery drain.
- Added (basic) ability to add custom udmf properties
- Changed buttons on object properties panel to bitmap buttons
Merge branch 'master' of https://github.com/sirjuddington/SLADE.git
Merge branch 'master' of https://github.com/sirjuddington/SLADE.git
Merge pull request #52 from alexey-lysiuk/map_no_bg_update

Disabled update when map window is in background
Merge branch 'master' of https://github.com/sirjuddington/SLADE.git
- Show line lengths on line draw and object edit
- Some more fixes for SFML 2.1 compatibility (still wonky though, might just drop sfml renderwindow and use wxglcanvas+ftgl in windows instead)
Fixed crash on object edit with no selection or hilight
Merge branch 'master' of https://github.com/sirjuddington/SLADE.git
- Added FTGL configuration to VS2012 sln
- Added glFinish after buffer swap on MapCanvas to reduce framerate choppiness with vsync
Fixed line length text display when using ftgl
Increase depth buffer size to 32 for wxglcanvas
Merge branch 'master' of https://github.com/sirjuddington/SLADE