Progated the -l option down to the Assembler class.
Removed a superfluous semicolon from dasm.cpp.
Added underscore to the and, or and xor instructions.

This is because they are reserved words in C++, and G++
complained when they were being used as variable names.
Fixed waf script to work on Linux.

It was passing MSVC specific options to the compiler.
Additionally, the script now conforms to the pep8 coding style.