Add double click support for save game selection
Add support for editor-save in SelectSavegameDialog
Change editor gui to use SelectSavegameDialog instead of SaveMapDialog
Make the EditorSession save function also show a dialog to choose the map name.

This is the way the save function in spsession works.
Remove SaveMapDialog, which is now unnecessary
Fixes #2046 - Fix boatbuilder eating the player's money
Swap comparison logic

Since `evt` is our input, this should make more sense.
Add trigger_close function in Dialog class
Merge pull request #2036 from ThePawnBreak/savegame-doubleclick

Add double click support for save game selection #1982
Defaultdict
More helpful warning on missing file
Add new directory in which to look for FIFE

After their repository move, this is pretty likely to be the folder
cloned into.
New files added from Unknown Horizons Translation Server based on templates
Commit from Unknown Horizons Translation Server by user Chris Oelmueller.: 0 of 785 strings translated (0 fuzzy).
Check for valid gettext plural forms (#2048)
More helpful logging of errors with translations

Should now actually print errors that happen, and also hint about the
fallback used. #2048
Commit from Unknown Horizons Translation Server by user Gallaecio.: 369 of 369 strings translated (0 fuzzy).
Commit from Unknown Horizons Translation Server by user Gallaecio.: 733 of 733 strings translated (0 fuzzy).
Commit from Unknown Horizons Translation Server by user Gallaecio.: 17 of 17 strings translated (0 fuzzy).
Copy `corn` icon to `grain`

Due to lack of more fitting icons. Fixes #2047