Work in progress: Category class and content provider

for recently-used categories list
Tweak column order...?
Stub adapter for the recent cats view...
Add XML/manifest bits for internal category content provider
Drop Parcelable interface, not needed
Initial stab at pulling cats from content provider

We don't put anything in the provider yet though. :)
Work in progress: hook up content provider for recent cats
Add DB updaters for Category table
Categories now save :D

Still to do:
* limit number of entries
* order by last-used
* show entries on the initial screen before searching
Use a single content provider client for all cat queries
Show used cats in MRU order
Use query conditions for the name lookup :D
Limit view of recent cats to 20
Use same limit for recent cats and cat search
Hide the "skip" message if we load up some recent cats
Fixups per Yuvi's notes
Remove generic update from categories provider
Compile fix for method that returns Void. :P
Fix regression in first-categorization experience

The skip message now shows when there are no recently-used categories.
Merge pull request #9 from brion/recentcats

Store and show recently-used categories list