It's the recommended way to set those, and is more portable
(automatically prepends -D for GCC/Clang and /D for MSVC).
We still use CPPFLAGS for some pre-processor flags which are not
defines.
Include paths are processed from left to right, so we use Prepend to
ensure that paths to bundled thirdparty files will have precedence over
system paths (e.g. `/usr/include` should have lowest priority).
The pattern and replacement matching behaviour has been changed purely
due to the nature of switching to a standards-compliant library.
One mistake in the previous behaviour was that named groups didn't have
a number. This has been corrected.
As names are actually just an alias of numbered groups,
RegExMatch::get_name_dict() is now get_names() and is a dict
referring to the group number it represents.
Duplicate names are enabled and the with the first matching instance
used.
Due the lack of a suitable equivalent in PCRE2, RegExMatch::expand() was
removed.
Re-wrote nrex as a module using godot-specific parts and new
features:
* Added string substitutions.
* Named groups are now supported.
* Removed use of mutable variables in RegEx. RegExMatch is returned
instead.
