Added TODO comments
Colorful body in thread buffer

If bodytext from message contains ANSI escapes (generated for instance with
color dump of elinks), now it parses the escapes to urwid attributes to
construct the output.

 alot.helper:
  - Added function parse_escapes_to_urwid()
    This generates a list with the text and the urwid attributes object.
 alot/widgets/thread.TextlinesList:
  - Call for parse_escapes_to_urwid() while constructing each line.
 alot/db/message.Message.accumulate_body()
  - Strip out ANSI escapes in order to correctly generate replies, forwards,
    bounces and new messages.
 alot/commands/thread.PipeCommand.apply()
  - For decoded format, call for accumulate_body() instead ov extract_body()
    in order to get rid of ANSI escapes (only useful really in thread mode).
Merge branch 'color_html_rendering'