Add support for transcripts and command records

[curiousdannii]

With Glk this should not be so difficult.

[curiousdannii]

Just realised that my handling of the transcript bit is extremely buggy.

@erkyrath Is it safe in general to request special input and char input in GlkOte at the same time? (I know that glkote-term can't, but I can probably fix that, and presumably would need to for Glulx games to be able to use it.) For ZVM though I think I will need to make it issue the input requests sequentially.

[erkyrath]

If you request specialinput, the rest of the UI is disabled so that the specialinput can act as a modal dialog. So all other input requests are legal, but on hold.

[curiousdannii]

Gotcha. I will have to ensure that ZVM's specialinput handler doesn't automatically start running VM code again unless it is meant to.

Edit: Actually glkote-term already disables other input when a special request is active! I hadn't fully understood all the code I wrote :P

[curiousdannii]

I think this is complete and working now. Suggestions or patches to make ZVM match other terps' log formats (especially for char input) are welcome any time.