Merge pull request #4 from nifgraup/master

initial support for gmvault mailbox format  ( fixes issue #3 )
Fix bogus unicodedecoderror when passed a binary string
Make mailbox loader more resiliant
Preparing the concept of editable mailboxes / a drafts folder
2013
Added GlobalPostingList to optimize IO related to incoming messages
Make index parser tolerate out-of-order input
Incrementally save changes to the index instead of all-at-once
Fixing minor buglets
Minor fixes to GlobalPostingList changeset
Refactoring to allow easy setup and message drafts, preparing composition commands
Do not crash even if invalid IDs are requested in view, extract, etc.
Basic editing of simple messages works
Fix charset handling in composer, prepare for attachments and recipients
Fix messages and error handling in composer
Adding attachments works
Complain nicely when attempting to edit or attach to read-only messages
Basic support for adding/removing/keeping attachments via. string composer
Fixing utf-8 encoding of config file, location of local/drafts mailbox
Rename global.dat to kw-journal.dat, make sure only local box is editable