The overall intent is to make writing a decompiler require less code
duplication.
"bits.hpp" and "stmt_enum.hpp" are replaced with "stmt_ins.hpp" which
is generated directly from dsp-notes.csv.
This also adds support for "#" characters prior to immediates.
nop may also now appear in an op_t. The parser no longer generates nop_t--this
is instead now represented as an op_t with a zero-length ops vector.
This also concedes that a lexer that returns std::vector is probably
the simplest API for the parser, but I will still continue to consider
alternatives.
