preliminary work with exparay
Add doc, test, and intents for exp_aray interface

NOTE: exparay.f contained mistake:
"b(i,j) = exp(b(i,j))" should be "b(i,j) = exp(a(i,j))"
Add doc, test, intents for multbycnst interface.
Modify awips.py to adhere to Sphinx formatting.
Preliminary work with derivative interface.
Add doc, test, intents for derivative interface.
Add doc, test, and intents for lintrans.f
Add doc, test, intents for dotvectors interface

Also cleaned up documentation from previous commits
Add doc, test, intents for powercalc interface.
Address feedback for previous commit.

Also:
DOC: Add 'Rows beyond ni will be zero filled.' where appropriate.
     Add 'float32' to result description where approriate.
     Add description of result sizes.
Merge pull request #19 from GregHat/master

Add doc, test, and intents for 6 functions.
There is additional small change that I flagged, but I think it can be fixed in the next check-in.