wxWindows regex
---------------
This is a version of Henry Spencer's regex, which was taken from the
source of TCL (Toolkit Command Language).  It implements POSIX regular
expressions and also supports Unicode and some Perl5 extensions.

The modifications made by the wxWindows team are as follows:

regcustom.h
-----------
Types and constants appropriate for our use of the library are defined
here.

regex.h
-------
This is unmodified. Note though, that a portion of it (clearly marked)
is copied from regcustom.h as part of the build process.

regc_locale.c
-------------
This module provides character classifications.

The current version from Tcl supports only a Unicode build. The
original code from Henry Spencer, on the other hand, was ASCII only.
Therefore, in order to support both, code from the ASCII version has been
incorporated into the Unicode version, conditionally compiled depending
on wxUSE_UNICODE.

The only non-trivial dependencies were: Tcl_UniCharToUpper,
Tcl_UniCharToLower and Tcl_UniCharToTitle. The implementations of these
have also been incorporated (from Tcl). These in turn depend only the data
tables in tclUniData.c (which is unmodified). At some point wxWindows
may have it's own Unicode character classification code, at which point
these should be used instead.

Other dependencies (on Tcl_DString) have been eliminated using wxWindows
wxChar functions.

The ASCII version has also been extended to support character
classifications based on the current locale rather than ASCII only.