Add support for Intel syntax

[NewDefectus]

It should be possible to switch between Intel and AT&T syntaxes using the .intel_syntax and .att_syntax directives, respectively. As mentioned in the page, these directives should have an optional argument prefix/noprefix, which specifies whether registers should be prefixed with % or not.

Switching to Intel syntax should include reversing the operand order of instructions, changing the directive syntax, not requiring a $ to prefix immediates, changing the memory operand syntax, using BYTE/WORD/DWORD/QWORD PTR to specify size instead of instruction suffixes, and using ; as a comment token instead of #.

The CodeMirror module should also support this new syntax.