fix for warning and content overlapping
tweaks

* allows for coordinating with animation with content size changes
* synchronizes animation to prevent crashes
* slides up newly opened section using updated content size
fix for handling last opened section when delegate is not fully implemented

When `accordion:openedSection:` is not implemented it was not setting
`_lastOpenedSection` which is necessary for the intended behavior to
slide up the last opened section.
Merge pull request #1 from brennanMKE/master

fix for warning and content overlapping
added immediatelyResetOpenedSections to reset a table view
revised immediatelyResetOpenedSections to just call reloadData
Merge branch 'brennanMKE-mytweaks'
Merging merging