CGA 90x30 Text Mode (720x240) support

[Bs0Dd]

MC6845 can be reprogrammed to use 90x30 (so it's 720x240 pixels) symbols instead of standard 80x25 (640x200).

Of course, MCE Blaster can't properly handle this resolution.

I know that this is an uncommon mode, but it looks like some demos utilize it. At least Area5150.

As I understand, Pico 1's memory isn't enough to do this, so it can only be made for Pico 2, but I think it's still a good idea, so users can watch demos through MCE Blaster.

[scrapcomputing]

I think we should be able to support this in Pico2 Manual-TTL. I will experiment with making the buffer larger.
Thanks for the feature request!