added a new "Antenna Gain" equivalency (Jy to K)
fixed equivalency call
add to __all__
fixed tests & examples as per @mdboom's comment
fixed docstring tests: reduce # of significant digits
same as previous commit, but for the <Quantity object.  Unfortunately,
this hides the units...
added some more clarification & references to the jytok equiv
fixed doctest
name change: jytok -> brightness_temperature
doc formatting change
added eqiv to changes
doc update (tb equiv)
documentation fixes in tb equivalency
doc fix attempt cont'd; intersphinx not working for quantity though
fixed example formatting
more docfixes; added direct link to Tools of Radio Astron
added another link in docs
omega_B->beam_area in code
nu->disp
Merge pull request #1327 from keflavich/tb_equiv

Added a new "Antenna Gain" equivalency (Jy to K)