Fix up the stage view's commit message text view

- stop the spelling error markers from being drawn over
    - allow undo/redo in the commit message view

PBCommitMessageView.m

@@ -13,9 +13,7 @@
 
 - (void)drawRect:(NSRect)aRect
 {
-	NSColor *originalColor = [self backgroundColor];
-	[originalColor set];
-	NSRectFill(aRect);
+	[super drawRect:aRect];
 
 	// draw a vertical line after the given size (used as an indicator
 	// for the first line of the commit message)
@@ -33,10 +31,6 @@
         line.size.height = aRect.size.height;
         NSRectFill(line);
     }
-
-	[self setBackgroundColor:nil];
-	[super drawRect:aRect];
-	[self setBackgroundColor:originalColor];
 }
 
 @end

PBGitCommitView.xib

@@ -21,7 +21,7 @@
 		</object>
 		<object class="NSMutableArray" key="IBDocument.EditedObjectIDs">
 			<bool key="EncodedWithXMLCoder">YES</bool>
-			<integer value="207"/>
+			<integer value="130"/>
 		</object>
 		<object class="NSArray" key="IBDocument.PluginDependencies">
 			<bool key="EncodedWithXMLCoder">YES</bool>
@@ -409,7 +409,7 @@
 																			<int key="NSTCFlags">1</int>
 																		</object>
 																		<object class="NSTextViewSharedData" key="NSSharedData">
-																			<int key="NSFlags">11235</int>
+																			<int key="NSFlags">3971</int>
 																			<int key="NSTextCheckingTypes">0</int>
 																			<nil key="NSMarkedAttributes"/>
 																			<reference key="NSBackgroundColor" ref="818038086"/>
@@ -1389,7 +1389,7 @@
 				<object class="NSMutableArray" key="dict.values">
 					<bool key="EncodedWithXMLCoder">YES</bool>
 					<string>com.apple.InterfaceBuilder.CocoaPlugin</string>
-					<string>{{1183, 504}, {852, 432}}</string>
+					<string>{{1091, 655}, {852, 432}}</string>
 					<string>com.apple.InterfaceBuilder.CocoaPlugin</string>
 					<integer value="0"/>
 					<integer value="0"/>

PBGitRepository.m

@@ -150,6 +150,11 @@ NSString* PBGitRepositoryErrorDomain = @"GitXErrorDomain";
 	return self;
 }
 
+- (BOOL)isDocumentEdited
+{
+	return NO;
+}
+
 // The fileURL the document keeps is to the .git dir, but that’s pretty
 // useless for display in the window title bar, so we show the directory above
 - (NSString *) displayName