CPLD: update RD4 & RD5 signals on rising edge of Fi2
File selector v2: add delays after enabling/disabling cartridge memory
File selector v2: zero-fill memory before executing .com
File selector v2: write explicit value to NMIEN

Change suggested by Piotr Fusik.
File selector v2: turn off Basic ROM before loading .com

Change suggested by Piotr Fusik.
File selector v2: simplify .com loading

Change suggested by Piotr Fusik.
File selector v2: reopen editor, set RAMTOP before running .com

Changes by Piotr Fusik.
File selector v2: send memory contents through SIO before running .com