Identify various flag labels and bit constants

[Rangi42]

After this, only four labels will be unidentified:

• wcd6d (110 uses)
• wcf91 (171 uses)
• wd0b5 (56 uses)
• wd11e (163 uses)

Of course, there are still many non-label constants left to be identified. In particular, flag bits and meaningful RAM values that should be going in the new ram_constants.asm file.