improve logic of syntax reading

[GoogleCodeExporter]

syntax options are reworked, and more straight/simpler logic.
outbound:
- default grammar options
- overruled by: envelope syntax
- overruled by: message syntax
- overruled by: frompartner syntax
- overruled by: topartner syntax
inbound:
- default grammar options
- overruled by: envelope syntax
- overruled by: message syntax
(I have no use case for partner syntax here)

new:
- use frompartner options; use case: multiple companies use same bots instance 
(eg different brands, takeovers, etc)
- bots remembers what syntaxes could not be read and does not try to read this 
again; reason performance, avoid excessive reading of non-existing syntaxes.

This might not be 100% upward compatibel; in x12 messages sometimes there is a 
diffent envelope version indicated. This was not used, but is used now.   

Original issue reported on code.google.com by hjebb...@gmail.com on 31 May 2013 at 1:17

[GoogleCodeExporter]

Original comment by hjebb...@gmail.com on 6 Sep 2013 at 4:54

• Changed state: Fixed

[GoogleCodeExporter]

Original comment by hjebb...@gmail.com on 10 Sep 2013 at 12:46

• Changed state: Done