1.12 Upgrade Guide

[scottgonzalez]

There are a few things left for the upgrade guide:

• Document all effects rewrite #10599
• Spinner deprecated _buttonHtml() and uiSpinnerHtml() methods #11097
• New APIs
  • form-reset-mixin #12638
  • slider index available in event handlers #7630
  • tooltip elements as content #9278
  • widget mixins #12601
• Remove the section about $.ui.intersect() being removed.
  • This was restored, but I don't want to update the upgrade guide until we release a version that has it restored.