parser: Change list syntax

[vitorarins]

list syntax should be like this: ["a", "b", "c"]. And unquoted strings will not work inside lists anymore.

So:

• instead of parenthesis (() we will use brackets([)
• instead of spaces( ) we will use commas(,)
• unquoted strings will not be accepted. Ex.: [ a, b, c ] will fail.

[i4ki]

I think we need a nashfix for that. Because it has a big impact on existing code base.