Update mairix to version 0.16.1. Changes include:

Update mairix to version 0.16.1.  Changes include:
 Home directory and environment variable expansion in the .mairixrc file.
 Add ^ word prefix to require substring search to be left-anchored.
 Add the capability to omit particular folders from indexing.
 Implement dot-locking on the database file.
 Display message path in warning messages from rfc822 parsing.