[alot] announcing bugfix release v0.21

[Patrick Totzke]

Good news everyone!

I have just tagged the bugfix release version 0.21 of my terminal GUI `alot`.
You can get a tarball here: https://github.com/pazz/alot/tarball/0.21

NEWS:

* avoid traceback infos from getting written on top of the ui
* new "--help" output, autogenerated manpage
* version string extracted from git for cli option "--version"
* command line subcommands: compose and search
* properly display multiple headers with the same key
* envelope.set option "--append"
* more detailed CUSTOMIZE docs
* multiple fixes for the envelope buffer
* exit on closing of last buffer is now optional
* die gracefully when config parsing fails
* random bugfixes in the ui
* determine attachments via the "Content-Disposition" header
* nicer alignment for messages in thread buffers
* deal with external commands as lists of strings instead of strings
* better filetype detection in attachments via magic numbers
* errbacks and correct calling of post-hooks for deferred commands
* add packaging info for debian
* envelope.headers stores lists of values for each key now
* default binding: 's' to 'toggletag unread' in search buffers

The bleeding-edge development version lives in branch 'testing' and is already
a few cool features ahead of this release. Check it out from
https://github.com/pazz/alot

Thanks goes to dtk, teyphoon, mortbauer and murks for fixes and bugreports.

Happy holidays,
/p