WIP: fix for wind direction binning

Previous logic in tinylib placed wind direction values on bin bounderies
rater than centers and did not "wrap around" at -180 degrees.
Work in progress. needs further clean up and testing.
Fix for wind direction binning

Clean-up and tests added/revised
Minor dusting
More dusting...
One more test fix
Merge pull request #22 from ms8r/wind-dir-bins

WIP: Fix for wind direction binning