Basic Navigation
Up/Down arrows use to navigate messages.
Tab/Shift-tab same as Up/Down arrows (outside edit mode)
Home/End focus first/last message
Space go to next unread message.
Left/Right arrows to switch focus between digest panel and wave panel.
Page Up/Down go to the next page in the panel [does not currently work, known bugs]
Ctrl-Space mark all messages read (focus must be on wave panel though)
