Mark messages as "S"een as well as read.

  This avoids messages in mutt showing as "O"ld.

  This fixes #49 / closes #49.
  Added machine-readable copyright file for Debian package.
  Searching for maildirs/messages is case-insensitive.

  This closes #50.
  Added new primitive: log_message().

  This will write to the logfile, when debugging support
 is present.
  Updated the build-dependencies and text.
  Typo fixes: cna -> can, currnet -> current.
  Mark the return code of system() and write() as explicitly
 ignored.

  Although this is a silly thing to do it will allow us to
 build cleanly when stack-protection is enabled.
  Build with fortify-source/stack-protection.

  Now that the return-codes of system()/write()/etc are
 ignored we can compile cleanly with this.
  Load from ~/.lumail.d/

  This means we don't load .lumail/config.lua twice.  Sigh.
  New release 0.10
  typo fix: teh -> the
  New primitive: message(), to return the path to the current message.

  This allows piping to commands, etc.

  Closes #51.
  Reverted message().  `current_message` exists.

  D'oh.

  The code I added & reverted was cleaner though; so replace
 the implementation of `current_message()` with it.
  Don't automatically append "(" to the user-defined completion
 options.

  This closes #52.
  Don't mark sent-messages as new.

  This fixes #53.
  When drawing maildir/index modes clear the left-most screen.

  We start showing indexes/maildirs are colum 2, and until now
 we didn't blank the first two characters.  This could cause some
 screen artifacts.

  Fixed now.  Always draw "  " at the start of the line(s).