Fix the chat widget's visibility when not logged in
Show OS notification when user is not logged in
Remove unnecessory header file inclusion in Menu.cpp
Made overlays thread safe for write operations, which solved a script
crash.
Added some missing locks to make Overlays thread safe for reading as well.
Use local viewer model for specular.
Added a new lock specific to deleting, and improved safety
Merge remote-tracking branch 'upstream/master'
Merge remote-tracking branch 'upstream/master'
Merge branch 'master' of https://github.com/worklist/hifi
Merge branch 'master' of https://github.com/worklist/hifi
Merge branch 'master' of https://github.com/worklist/hifi
separate style handling for chat area and its context menu.
Fix chat scroll bar widget jumping

Hovering over the chat window's scroll bar was causing it to jump
around. Replaced the 12px style spacing that was causing the problem
with a widget-based solution.
Fix chat window scrolling to stay at bottom

Stay at bottom window when:
- There is new chat.
- People come and go from online list.
- Chat window hides and restores when application focus changes.
- Interface is minimized and restored.
Add support to load script engines not based on a file
Add console to menu
Add custom evaluation of commands in ScriptEngine
Add JSConsole
Merge branch 'master' of git://github.com/highfidelity/hifi into 19648

Conflicts:
	interface/src/Application.cpp
	interface/src/Application.h