Julia Version	Unit Tests	Coverage

The StrRegex package adds Regex support to the Strs package, as well as fix some issues present in the base Regex support.

• Thread-safe support
• Allows the whole range of compile and match options
• Supports both UTF and non-UTF strings
• Supports strings with 8, 16, and 32-bit codeunit sizes
• Correctly sets the NO_CHECK_UTF flag based on the string type

It is working on both the release version (v0.6.2) and the latest master (v0.7.0-DEV).

This uses a R"..." macro, or RegexStr constructor, instead of r"..." and Regex as in Base.

Some changes might be needed in Base to make it work with the r"..." regex string macro and Regex type, because there are some fields missing that would be needed to handle arbitrary abstract string types).