Cache ThemedTypefaceHelpers for better performance

This fixes the jank seen when scrolling through the list of fonts
as well as the bad characters that show up from time to time.

Change-Id: I0002a92edb154276035015fc7836dd72ea43dbf7
Merge branch 'cm-11.0' into kk_mkt

Conflicts:
	src/org/cyanogenmod/theme/chooser/ChooserBrowseFragment.java

Change-Id: Ib0120365c6f5c2aaa7bf600e02a461eb494963fa
ThemeChooser: Code Cleanup

Change-Id: I279ea80ebea0c480233a3c6269f5d413c5228fa3