regex literal options

Regex literals should support options as in JavaScript and other languages (non-literal on Perl and Python) :

e.g:

/ok/i.IsMatch("OK")  //case-insensitive regex => it matches

Valid options :

• g - Global (no-op on .NET)
• i - Ignore case
• m - Multi line
• s - Single line (dot includes \n)
• x - ignore pattern whitespace (and allow comments)
• l - locale-aware (no-op on .NET, since (l)ocale-aware by default)

• n - culture-(n)eutral [boo-specific]
• c - compiled regex [boo-specific]
• e - explicit capture [boo-specific]