new tests for si/cgs conv. of quant. w/o dimension

I added two tests for the conversion of 'unitless' quantities
to the SI and CGS systems (Issue #1150).
Merge pull request #746 from iguananaut/fix-doctests

Test doctests
Merge pull request #1214 from terben/unit_dimensionless_branch

Fixed handling of dimensionless quantities in UnitBase/to_system - Issue #1150
example->examples in docstrings
Merge pull request #1217 from kbarbary/sphinx-inline-code-css

Sphinx inline code css
Remove unneeded continuation marks somebody added to one of the imports.
Simplify conversion to np.float for input list
No longer try to preserve data type of input array if it is not
some type of floating point.
Add wcscheck utility

Add documentation for wcslint
Fix for Python 2.6, which is missing PyErr_NewExceptionWithDoc
Update for astrofrog's comments
import units in doctests
docstring fixes cont'd
minor change to CHANGES - cleaned up typos, didn't remove the line
though...
Fix Python 3 issues
added ellipsis to make py3 greater-precision printing work...
Fix #1223 -- resource tags are not unnesting correctly on parsing.  Added test based on @RayPlante's example in #1223
Don't cause an exception during configuration file building if matplotlib is installed, but not Sphinx.
Simplify class comparison in tai_difference
docs update