Make a start on the MFDs
JS support for setting MFDs

PS.setMultiFunctionText(key, string)
PS.setMultiFunctionDisplay(index,key)
PS.multiFunctionDisplays // count

Second function may end up as debug-only.
Keys for player to change MFDs

';' to change MFD content, ':' to select the next MFD if HUD has >1
':' now allowed as an SDL key, though more accurately shift-; now allowed