Add T-Regx

[danon]

Advanced library for Regular Expressions in PHP: https://t-regx.com/

It:

• Maps warnings, errors, flag errors, C-like errors (preg_last_error()), return type values and other unexpected situations in PHP regular expressions to exceptions.
• Fixes bugs and incosistencies (fixed in later versions of PHP or not at all)
• Prevents fatal errors from preg_() methods (for example, by throwing InvalidArgumentException).

Additionally:

• Provides higher-level API for matching, replacing, spliting, validation.
• UTF8 support out of the box
• Removes false positives (in PHP regular expressions, missing group, unmatched group and matched empty string are identical, T-Regx distingushies them)
• Provides API for chained and multiple patterns.
• Provides patterns without delimiters, so pattern('\d+'), instead of preg_match('/\d+/');
• Provides Prepared Patterns, an abstraction for building patterns with user data
• Functional interface
• More advanced methods, for example reacting to replacement not being done, optional matches, injecting strings into groups, etc.

About the project:

• PSR4 followed
• Semantic versioning
• PHP 7.1 and 8.1 compatible
• Composer installable
• Developed with real TDD in mind (you can see what I mean by "Real TDD" in Contributing.md)