Add MasmAssembly

A complete syntax highlighting plugin in MASM/JWASM syntax.

OK there are miles to go before it can be called "complete". It just has the common instructions and directives. I believe it contains all 80386 non-privileged instructions. Full x86/x64 registers. Other than that it's incomplete. I tested it with my codes and didn't find any big issue. So I guess that should be enough for most people.