Remove bounds from Angle class
Add Angle.wrap_at() method and tests
Add Angle.within_bounds() + small fix to Angle.wrap_at()
Improve angle arithmetic in hour_angle and lst
Add in_place kwarg to wrap_at()
Add Lat and Lon subclasses of Angle
Fix mistake in calling wrap_at, forgot the in_place arg
Change Lat/Lon to Latitude/Longitude
Add Latitude tests
Add longitude tests
Fix problem wrapping a 0-d Longitude object
Move RA.hour_angle and RA.lst methods to standalone functions
Remove RA and Dec subclasses
Remove useradec and anglebounds from _initialize_latlon()

These two args are no longer needed in the simplified system of
just having Longitude / Latitude classes that function as
RA / Dec, Az / Alt, and L / B respectively.

One notable API change is that Galactic "l" is now in 0 to 360 instead of
-180 to 180.  This required a test change.  From what I can see in
the literature Galactic "l" should be 0 to 360.
Add/update docstrings for Latitude, Longitude, Angle
Update docstring / doctest example for python 2 / 3 compatibility
Update angle docstring examples to not look like doctests
Change Angle.within_bounds to is_within_bounds
Latitude/Longitude docstring fixes
Remove Angle.lst_to_hour_angle and hour_angle_to_lst functions (see #1385)