In the data operand edit section, walk through selecting a single
byte vs. multiple bytes when you want to set a multi-byte format.
(inspired by issue #41)
If PTR is defined as an external symbol, we were automatically
symbol-ifying PTR+1. Now we also symbolify PTR+2. This helps with
24-bit pointers on the 65816, and 16-bit "jump vectors", where the
address is preceded by a JMP opcode.
Removed the "AMPERV_" symbol I added to make the tutorial look
right.
