Making keywords optional, case-sensitive tags, viewers now work on CygWin, many fixes

Hi Edward,

here is a batch of changes. At least one of them is controversial - I made tags to be case sensitive when added or removed from the document in 'sort' function. If you don't agree let me know and I will make it configurable.
I also changed vim commands MinionOpen and MinionOpenAll (new command) to behave the same way as minion shell command line. Let me know if any questions or concerns.

Cheers

-Pavel