All objects requiring a font now use the NSFontManager defaultFontManager.

PLThemeable now requires adherents of the protocol to implement the updateFont: method. PLTabViewController sets itself as the NSFontManager defaultFontManager target and in the changeFont: method, sends the updateFont: message to all of its viewControllers. LiasisAppDelegate sets the font to Menlo size 14. All objects that were defining the Menlo font have been modified to access the shared font manager.
Tab subviews are now made first responder on tab switching.

In PLTabViewController, make the window's first responder the view controller of the new active tab. Both view extensions controllers (PLEditorViewController and PLInterpreterViewController) implement the NSResponder method becomeFirstResponder. In each, they make their text view the first responder of the window.

Reorganized the order of events in LiasisAppDelegate applicationDidFinishLaunching so that the final step is to set the active tab in the tab view controller, which now assigns first responder.
Improved calculation of the column ruler location in the text editor view.

The font width is now calculated as the font maximum advancement width. With this measure, the scroll view point origin is no longer needed.
The column ruler in the text editor view now responds to font changes.

PLEditorViewController now has a columnRuler property. Its setColumnRuler method is modified slightly to use the shared font manager and update the columnRuler value. In the updateFont: method, call setColumnRuler with the current column ruler value to update its position.
Improved font manager support for autocomplete view.

The autocomplete text view font is now always set to that of the superTextView prior to being displayed. If the view is visible when the font changes, update it to the new application shared font.
The updateFont: method is now optional in the PLThemeable protocol.

PLFileBrowserViewController and PLTabViewController no longer implement the method since they previously did nothing.
Moved the sharedFontManager target to be LiasisAppDelegate rather than PLTabViewController.
Merge branch 'feature-font_manager' into develop

The merging branch uses the NSFontManager sharedFontManager to regulate an application-wide font. An updateFont: method is added to the PLThemeable protocol for class to optionally implement in order to know when the font changes.

Conflicts:
	Liasis/Liasis/LiasisAppDelegate.m
	Liasis/Liasis/TextEditor/PLEditorViewController.h
	Liasis/Liasis/TextEditor/PLEditorViewController.m
PLEditorViewController no longer conforms to the NSMenuDelegate protocol.

It became unnecessary for it be a NSMenuDelegate when PLNavigationPopUpButton was created and added to LiasisKit.
Improved the category factory methods to convert Python sequences/dicts to Objective-C types.

Both methods now enumerate over the key/value pairs (dictionaryByEnumeratingPythonDict:withBlock:) or sequence objects (arrayByEnumeratingPythonSequence:withBlcok:) using a block. Updated PLPythonIntrospectionController and PLSyntaxHighlighter to use these new methods.
Fixed a memory error in PLAutocompleteViewController.

In the displaySelectedCompletion method, move the two release calls into the bail section, after both attributed strings have been inserted into their text views. This fixes a memory error that occurred with a new document, when typing a single character that displayed the autocomplete view.
Added an NSString category to find a word at an index.

The category NSString+wordAtIndex provides two instance methods: one to find the word range and one to return the word itself. Updated PLAutocompleteViewController to use this new method in lieu of several functions it already used for this functionality. Additionally, cleaned up many methods in PLAutocompleteViewController by simplifying them due to this change.
Fixed a memory issue in the navigation popup button.

In the reloadData method of PLNavigationPopUpButton, retain the currently selected title (which is used for restoring the selection after updating the menu).
Fixed the high CPU usage from the line number view.

In PLLineNumberView, the bounds of the ruler view were changed in the drawHashMarksAndLabelsInRect: method. This seems to cause drawing again, resulting in too many calls to drawRect: and a high CPU usage. To fix, the PLLineNumberView now observes the NSViewBoundsDidChangeNotification of the scroll view's contentView. In the new boundsDidChange: method, perform the calculation to update the bounds (same calculation that was in the drawing method).