NEW FEATURE: add text overlay mode

[cyberboy666]

the idea is to display either text files from the usb/sd or live input with a usb keyboard attached.

the pots/cv would control displacement and/or color

there would be two new interface pages (i think to the right of the effect page):

TEXT

selecting which text file to display from file list - or choose LIVE (if keyboard attached - a special key on keyboard would save current live text to a file) - pots here control text displacement (x_pos, y_pos, width, height)

FONT

selecting which font that text is in from file list - pots here control text color(hue, sat brightness, alpha)

while in TEXT/FONT pages the FX button will toggle the text on/off instead of the effect...