Support bigger set of the regex syntax

[eerimoq]

The regular expression module supports most commonly used regex syntax, but there are a few important parts missing. Those should be implemented.

• Beginning ('^') and end ('$')of line.
• Alternatives ('|').
• Groups ((...)).
• Multi line to match beginning and end at every newline.

Also, refactor and remove debug prints to reduce the code size and make the code more readable.