Extend ADD to include E and F registers

[craigthomas]

Extend the ADD mnemonic to allow for E and F variants. Adds the byte of the specified memory location to the register, and stores in the register.

ADDE:
Immediate - $118B, 3 byes
Direct - $119B, 3 bytes
Indexed - $11AB, 3+ bytes
Extended - $11BB, 4 bytes

ADDF:
Immediate - $11CB, 3 byes
Direct - $11DB, 3 bytes
Indexed - $11EB, 3+ bytes
Extended - $11FB, 4 bytes

The command works with the following syntax:

ADDE #$7A

Example:

$11 8B 7A     ADDE #$7A