MapTileset SourceDirectory ends with '/' to match the FRB standard.
Fixed crash occurring when trying to get the number of tiles wide on a tileset that has a tile width of 0.
Added support for right-click adding Tilesets in the editor (before it could only be done in the tool).
Tileset displayer now sets the Sprite Width and Height instead of leaving it at 0 - this is in response to the latest Gum rendering changes which require a width  and height.
Fixed crash that would happen when the combo box for entities would try to refresh when there was no tile selected.
Simplified the code for adding new tabs to the editor - used by the new command line control in the Glue plugin.
Adding a new tileset results gives the user options for tile width, height, margin, and spacing.