Removed callback event based on change in xlim or ylim - this is so the ParasiteAxes class can be used in future. Now, tick separation is computed on the fly if needed, from the WCSLocator.
Removed callback event based on change in xlim or ylim - this is so the ParasiteAxes class can be used in future. Now, tick separation is computed on the fly if needed, from the WCSLocator.

git-svn-id: 83a0274dba4329d458142e4079227af35a786d9d@78 2f3f69f2-b874-4715-96d5-35985bcb53a6

allisony/aplpy,mwcraig/aplpy