Persist SerialDisk Atari TSR after warm reset

[z80andrew]

An Atari warm reset reinitialises the disk vectors which causes SerialDisk to stop working.

Investigate how to restore these if a warm reset is detected.

[z80andrew]

See static void run_reset_resident(void) in https://github.com/emutos/emutos/blob/master/bios/bios.c

[z80andrew]

I've created proof-of-concept code in the wiki. This can now be incorporated in the SerialDisk startup code.