Port lexer and parser from the PowerShell repository

[ForNeVeR]

While our recent struggles with the lexer and the parser so far weren't so fruitful (e.g., see #236 and #258), I have an idea of a radical improvement.

What if we try to port the whole lexer and parser from the actual PowerShell repo?

Let's see the following classes:

• System.Management.Automation.Language.Tokenizer
• System.Management.Automation.Language.Parser

And see if it's possible to port them as-is (could be very tricky of course, but we can try!)

This will guarantee we have the last and the most correct definitions of everything in the original repo.

Our current definitions are not bad per se, but they are created from old PowerShell spec and thus are very outdated.

And the new spec, unfortunately, doesn't exist.