Change subtitles to use sound duration in per character display

@BrettASwift @kadst43 ~~Timing's off, at least on my end, but the functionality is there.~~

EDIT: Brett figured out the timing difference problem.

Uses virtual-world-framework/vwf#281
@kadst43 mentioned that it might be good to display the character name immediately (i.e., "[ROVER]: ") and just print the actual subtitles over time. You'll want to split the message and just use the VO text for this calculation.