Fix entry not opening on first focus
Merge pull request #147 from Blue-Shadow/master

Added a missing "MapBackground" property to the mapinfo config.
Changed the way window size/position saving works

Now uses a new 'window_info' section in the config rather than cvars, which will allow the feature to be extended to other windows/dialogs without needing to add a bunch of extra cvars.
Remember the size of various dialogs between sessions

Added new 'SDialog' base class similar to STopWindow, but for dialogs, which automatically uses saved window size info
Merge branch 'master' of https://github.com/sirjuddington/SLADE.git
Fix saving of UDMF sectors with 0 light level
Don't save map launcher dialog size for now, doesn't work correctly

...because it can either show the map list+preview or not
The plus key char is no longer different in windows and linux, apparently
Disable the script editor if the current game configuration doesn't support scripting
Fix assert in BrowserWindow class

Opening of Things Browser no longer triggers this assert within wxWidgets:
src/generic/treelist.cpp(1128): assert "col < GetColumnCount()" failed in DeleteColumn(): Invalid column index
Merge pull request #149 from alexey-lysiuk/fix_assert

Fix assert in BrowserWindow class
Fix script editor not having titlebar when docked
Add object mirror (horizontal/vertical) feature

Will also mirror directions when things are mirrored, and flip lines when not in vertices mode. Default shortcut keys Ctrl+M for horizontal and Ctrl+Shift+M for vertical. Also added to toolbar and menus.
Add mirror checkboxes to object edit panel
Don't draw line lengths on object edit

Doesn't really work with mirroring, and gets kinda cluttered anyway - might make it so that when you mouse over a line it shows the length instead
Shift+click during paste doesn't end the paste operation

Allows something to be copy+pasted multiple times more easily
Add option to remove invalid lines on sector delete
Update lines VBO when any line is modified
Fixes for tag edit

- Only update hilight on mouse click if mouse state is normal, was causing tagged list to be cleared during tag edit
- Refresh tagged list on ending tag edit
Always center SDialog on parent when shown