FPGA/cx4: remove init file (debug code) from program ROM block ram
Menu: move warm start signature to block RAM; initialize WRAM on cold boot
in-game hooks: ack IRQ, fix rotating of controller read enable mask
firmware: use meaningful initial MSU1 state
add/use some constants
Implement temporary hook disable after SNES reset

As was observed with the help of a number of users, many games trip over
the in-game hooks especially at boot-up. This feature keeps the hooks
disabled for 10 seconds after SNES startup or reset.
FPGA: reconstitute more aggressive SNES control signal filtering; unify edge detection and data buffering