It feels wrong to return a dumb LLInstanceTracker subclass* from getInstance()
when we use std::shared_ptr and std::weak_ptr internally. But tweak consumers
to use 'auto' or LLInstanceTracker::ptr_t in case we later revisit this
decision.

We did add a couple get() calls where it's important to obtain a dumb pointer.

phase 1, removal of most of llnotificationhandler

refactored LLWindowShade into seperate file
improved layout of dialog
improved dialog resizing logic
Tab and Enter keys now work as expected in windowshade form
added "modal" capability to window shade
added HTTP Auth notifications to MOAP

initial support for XUI auth dialog

popup blocking notifications now handled in all web_browser instances, not just llfloatermediabrowser

added web popup notification overlay

Result of svn merge -r107256:107258 svn+ssh://svn/svn/user/phoenix/license_2009_merge into trunk. QAR-1165

Result of svn merge -r71162:71205 svn+ssh://svn/svn/linden/branches/new-license into release. only changes files which are not deployed or the comments section of code.