FPP 7.5 Virtual Matrix Overlay Sub Model State

[wjenkins364]

Created an overlay sub model of an overlay model for 'a virtual matrix. If a full overlay state is used the message is displayed with a black background on the submodel. However the black background will not go away unless FPP is restarted. If a transparent state is used the message is unreadable.

After a reboot or restart, if an overlay message is sent to the virtual matrix using the transparent state and then an overlay message is sent to the submodel,  the state used is from the overlay model message.