enyo.List changes:
* use this.log instead of enyo.log for better messages
* remove unneeded check when adjusting page height during rendering
* have scroll() cache last position to avoid double work
Update enyo.List.getPageHeight to return better guess for unrendered pages
enyo.pageForPageNumber now takes optional parameter to tell it to range check the page number
enyo.updatePageHeight doesn't set bad height when original page has been removed from rendering

Enyo-DCO-1.1-Signed-Off-By: Ben Combee (ben.combee@palm.com)