Improved hifi:// style URL scheme handling.

First steps towards implementing #1463.

 - Moved url parsing code from Application::event to
   Menu::goTo(QString).
 - Handle destination component of URL as either a @username,
   #place, or x-xx,y-yy,z-zz style coordinate.
 - Added support for entering hifi:// style URL into @ invoked
   goto menu option.
merge upstream/master into "improved URL scheme"

Conflicts:
	interface/interface_en.ts
merge upstream/master into "improved URL scheme"

Conflicts:
	interface/interface_en.ts
Manual merge
Merge branch 'master' of https://github.com/highfidelity/hifi into HEAD

Conflicts:
	interface/interface_en.ts
	interface/src/Application.cpp
Fix crash: don't simulate until geometry exists
Merge pull request #2595 from AndrewMeadows/avatar-interaction

Fix crash: don't simulate until geometry exists
Informed users who want to chat they have to log in first.
Merge pull request #2596 from ddobrev/master

Informed users who want to chat they have to log in first
Remove translations for now, but use correct translation keys for the only
translations we had (days/weeks/etc.)
Don't refer to the QM file.
Merge pull request #2598 from ey6es/master

Remove translations for now, but use correct translation keys for the on...
Changed FstReader categories to place models in the right dirs