Added built-in attributes for done, due, priority, estimate, flagged, and progress.

Decided I needed to really build a bunch to help drive API design.

The Calendar extension changed in quite a few ways. Default behavior is now to filter. Drag to filter multiple days. Double-click or Return for the old behavior of creating a day for selected row(s).

• Added the new Attribute Palette
• Added value pickers, including a calendar
• Added Actual Size attachment display mode
• Added attachment management to Document Info
• Added a message in the editor when a filter matches nothing
• Improved scrolling speed in big documents
• Improved spell checking to stay out of the way
• Fixed typing in big documents slowing as the window gets taller
• Fixed a performance issue with Japanese and other IME input
• Fixed unused attachment files to move to the Trash on close
• Fixed a long filter query overflowing the toolbar
• Fixed selection not covering a badge wrapped onto its own line
• Fixed lone badge on a wrapped line sitting low and growing row

For extension authors: lots of changes in attributes, badges, summary, menu, and picker APIs. They all interact and as I implemented the built in attributes I kept finding changes to make. Likely still some loose ends, but I’m using these APIs to implement all the built in attributes, and generally they seem to be working well. Biggest change from previous API is menu is now much simpler. No embedded calendar or other elements, just plain menu items. Instead there is a new picker API that allows picking specific values, such as dates or durations.