XAP: add missing opcodes

[XVilka]

These are taken from the XAP test binary:

• 0c04
• 0bfd
• 0ffe
• 0ffd
• 0ffb
• 0ffa
• 0ff9
• 0bf7
• 0bfb
• 0bf9
• 0be0
• 0bea
• 0fe0
• 0900
• 0bf6
• 0fea
• 0bf1

[wargio]

so i was looking to the specs yesterday and those having the first 4 bits at zero on the second byte are part of the relative jumps see: https://github.com/SamL98/xap2/blob/master/data/languages/xap2.slaspec#L77
also some documents that can be found on the archive.org website describes the opcode and seems that XAP1 to XAP4 are backwards compatible (XAP5 seems more complex with proper registers) and the opcodes are very simple to decode.