Show warning for floating-point/integer conversion except if the quantity is truly dimensionless (i.e. unit == u.dimensionless, but not e.g. u.m / u.km).
Add configuration item, and avoid unnecessary import
Renamed configuration item
Added docs about float/int/numpy conversion
Compare units directly to pre-computed dimensionless object.
Use a better test for dimensionless of units in numeric conversions
Fix config item description
Fix function syntax so they are recognized by intersphinx
Use is_unity
Define _is_unity convenience function
Fixed logic bug
Improved _is_unity as suggested by @mdboom
Update comment regarding _is_unity test
Merge pull request #669 from astrofrog/unit/fix-float-conversion

Conceptual issue with float conversion when quantity is dimensionless