configure mbnames in a per account basis #428

[offlineimap at 927589452.de]

Hi,

so i looked into the code base and was curious on what the best way was
to solve this; I see the following options:
-resolving the mbnames_* in accounts.py and providing it to
mbnames.py as an argument
-resolving the mbnames_* in the mbnames.py by resolving the config
section for the 'Account' which is already provided.

Another Problem i would love you opinion on is:
should the general mbnames file still be written when we are using
custom files ?
should we have another switch like mbname_main or so for that?

Thanks for your Input
"J"