Add set_ticks_visible and set_ticklabel_visible
Add set_ticks_visible and set_ticklabel_visible

Give users ability to easily hide and re-show ticks and ticklabels for a
given axis with CoordinateHelper.

Fixes astrofrog/wcsaxes#169

lpsinger/astropy,mhvk/astropy,kelle/astropy,kelle/astropy,dhomeier/astropy,pllim/astropy,pllim/astropy,saimn/astropy,joergdietrich/astropy,lpsinger/astropy,AustereCuriosity/astropy,larrybradley/astropy,aleksandr-bakanov/astropy,astropy/astropy,astropy/astropy,kelle/astropy,stargaser/astropy,StuartLittlefair/astropy,mhvk/astropy,bsipocz/astropy,aleksandr-bakanov/astropy,kelle/astropy,tbabej/astropy,tbabej/astropy,funbaker/astropy,aleksandr-bakanov/astropy,stargaser/astropy,lpsinger/astropy,joergdietrich/astropy,StuartLittlefair/astropy,MSeifert04/astropy,AustereCuriosity/astropy,stargaser/astropy,astropy/astropy,pllim/astropy,dhomeier/astropy,bsipocz/astropy,tbabej/astropy,pllim/astropy,AustereCuriosity/astropy,joergdietrich/astropy,astropy/astropy,funbaker/astropy,larrybradley/astropy,joergdietrich/astropy,DougBurke/astropy,saimn/astropy,lpsinger/astropy,joergdietrich/astropy,AustereCuriosity/astropy,saimn/astropy,MSeifert04/astropy,larrybradley/astropy,aleksandr-bakanov/astropy,mhvk/astropy,kelle/astropy,saimn/astropy,MSeifert04/astropy,funbaker/astropy,DougBurke/astropy,mhvk/astropy,StuartLittlefair/astropy,DougBurke/astropy,funbaker/astropy,StuartLittlefair/astropy,pllim/astropy,astropy/astropy,mhvk/astropy,larrybradley/astropy,larrybradley/astropy,tbabej/astropy,DougBurke/astropy,dhomeier/astropy,MSeifert04/astropy,stargaser/astropy,lpsinger/astropy,AustereCuriosity/astropy,bsipocz/astropy,StuartLittlefair/astropy,tbabej/astropy,bsipocz/astropy,saimn/astropy,dhomeier/astropy,dhomeier/astropy