Replace ARB RegExpr with c++ native regex

[aboeckma]

C++11 contains a native regex library. There is absolutely no need to have our own regexp library in ARB. The native regex is well documented and tested. Additionally it has the huuuge advantage that other people use it as well.

[westram]

ARB uses the POSIX regex functions from the standard library, which are also well tested and have the huuuge advantage that other people use it as well.

The RegExpr in ARB is just a wrapper around calls to the POSIX functions. Its main purpose is to ensure that the regular expressions (as entered by or as written in -scripts) remains strictly unchanged.

When Arb is C++11-only (some day), the RegExpr-Wrapper internally could use C++11-regexprs - in which i don't see any advantage.

If the RegExpr-Wrapper is insufficient for some needs, use the POSIX regexpr directly.

[aboeckma]

Oops sorry! Didn't dig deep enough to notice that it wraps posix calls.