Misc minor improvements

Open dialogs now filter by correct file extensions

Sort sprites by name (instead of disk order)

Better handle blank author names in zspr files.

Sort paths by name. (Otherwise the Bomb shop entry if present looks
wrong)

BaseClasses.py

@@ -781,7 +781,7 @@ class Spoiler(object):
             outfile.write('\n\nPaths:\n\n')
 
             path_listings = []
-            for location, path in self.paths.items():
+            for location, path in sorted(self.paths.items()):
                 path_lines = []
                 for region, exit in path:
                     if exit is not None: