GUACAMOLE-288: Add support for multi-monitor connections on RDP.

[corentin-soriano]

Anyone who wishes can test and feedback will be appreciated!

Requires using this branch on guacamole-server: apache/guacamole-server#560

• Display each monitor in separate window.
• Secondary windows automatically resize to the dimensions of the main window.
• Display user consent button to switch all window on fullscreen when the main window fullscreen is enabled.
• All monitors are on the size of the main window and ordered from left to right (left monitor is the primary).
• Handle CTRL+ALT+SHIFT in secondary monitors (open the menu on the main window).
• Close secondary monitor on client disconnect.
• Admin can limit the usage of multi-monitors on each connection.
• Drag and drop between windows without having to release the click and resume on the other side.

Admin settings:

Add new monitor:

Multiple monitors opened:

[stephzero1]

wow this is huge! i will test asap