Changes named sub-expressions to use different hashing scheme: high order bit is now always set to clashes between hashes and indexes don't happen until 2^30 or 2^62 sub-expressions in 32 and 64 bit code respectively.
Changes bitmask of seen sub-expressions to use dynamic storage for sub-expression indexes above 64.
Adds tests for the above.
Fixes https://github.com/boostorg/regex/issues/75.
2) Changed std::copy calls on VC8 to avoid "dangerous code" warnings.
3) Moved backreference and octal escape code into line with POSIX-extended requirements.
4) Changed match_results leftmost-longest rules to stop unnecessary std::distance computations (an optimisation for non-random access iterators).
5) Changed C lib calls to use "safe" versions of string API's where available.
6) Added many new POSIX-extended leftmost-longest tests, to verify the above.
[SVN r27880]
