Release 0.6.4

Major changes, unfortunately mostly internal and hidden. The whole shader framework, and alot of the core as a result, has been refactored. Code is quite a bit cleaner and more importantly access to the majority of core functionality is now via interfaces (letter/envelope classes).

Addition of aqsltell tool, whose output matches sloinfo and slctell.

Compress output files.

See changes for complete list of upates.