[#179] Refactored folder deletion so that it uses selection in the core's directory_tree instead of using the one from the GUI layer.

cocoa/base/DirectoryPanel.m

@@ -105,7 +105,7 @@ http://www.hardcoded.net/licenses/bsd_license
     NSIndexPath *path = [outline selectedIndexPath];
     NSInteger state = [outline intProperty:@"state" valueAtPath:path];
     if (([path length] == 1) && (state != 2)) {
-        [_py removeDirectory:i2n([path indexAtPosition:0])];
+        [[outline py] removeSelectedDirectory];
     }
     else {
         NSInteger newState = state == 2 ? 0 : 2; // If excluded, put it back

cocoa/base/PyDirectoryOutline.h

@@ -11,4 +11,5 @@ http://www.hardcoded.net/licenses/bsd_license
 
 @interface PyDirectoryOutline : PyOutline
 - (void)addDirectory:(NSString *)directoryPath;
+- (void)removeSelectedDirectory;
 @end

cocoa/base/PyDupeGuru.h

@@ -15,7 +15,6 @@ http://www.hardcoded.net/licenses/bsd_license
 - (PyResultTable *)resultTable;
 //Actions
 - (NSNumber *)addDirectory:(NSString *)name;
-- (void)removeDirectory:(NSNumber *)index;
 - (void)loadResultsFrom:(NSString *)filename;
 - (void)saveResultsAs:(NSString *)filename;
 - (void)loadSession;