Fixed bug in the RecentManager

The bug was due to a double free of a GtkRecentInfo
stored as a named field of a GtkWidget.
Also added some documentation to the RecentManager

Signed-off-by: Wilson Brenna <wbrenna@uwaterloo.ca>
Manual patch of @x2b bc94214b1
Manual additional lock patch from @x2b 33ef0b4654
Fixed compiler error

Signed-off-by: Wilson Brenna <wbrenna@uwaterloo.ca>
Fixed an error in the InsertsUndoAction

Redoing the insert should add the element to the
layer, not remove it.

Signed-off-by: Wilson Brenna <wbrenna@uwaterloo.ca>
Rewrite of the "Export as..." dialog

Signed-off-by: Wilson Brenna <wbrenna@uwaterloo.ca>
Notify the settings of the changed save path

Signed-off-by: Wilson Brenna <wbrenna@uwaterloo.ca>
Improved the UndoRedoHandler

There was a small bug in the routine determining whether
a file is changed. To reproduce: Perform an action, save,
undo and redo. The file shows up as changed even though
it is not. Should be fixed now.

Signed-off-by: Wilson Brenna <wbrenna@uwaterloo.ca>
Merge branch 'master' into addpoppler
Removed ampersands from mutex in InputHandler.