[sane-devel] Some minor fixes of manual pages comitted

[Henning Meier-Geinitz]

Hi,

I have just comitted some fixes in the manual pages of several
backends. All these "bugs" were mentioned in the TODO list for quite
some time. Most of these were spelling mistakes, formatting issues or
mentioning sane-devel without further comments.

If I missed anything or you don't like a change please contact me.
I didn't check every man page for every detail and also left out the
more complicated things.

Bye,
  Henning