a.out padds the text section with 0-bytes, which where interpreted
as 0x00 0x00 instruction and occasionally as a single 0x00 byte. Add
logic to ignore single 0x00 bytes and to remove dangling 0x00 0x00
instructions at the end of the instruction vec, so only the 'actual'
instructions are presented in the end. Also adjust visibility of
methods, so only the truncated instructions will ever be presented.
Of course, this could remove an actual `0x00 0x00` instruction from the
end, but they would not have any effect on execution anyway.
While implementing some more mnemonics and testing
them, it was clear that modrm parsing was wrong.
Now reg to reg and immediates, together with
GPR1 interpretation should work as expected.
GPR1 interpretation can currently not be merged
into the modrm function, as with the current
abstraction the REG needs to select the correct
mnemonic, for which we need to also know the second
operand, which will only be parsed afterwards.
But this will be incorporated at some point, this
just marks the first working state.
