0.23.0
rename src/make_dafsa.py to src/psl-make-dafsa, add documentation
configure.ac: improve handling of dependencies found via pkg-config
Add NMake Makefiles for Visual Studio builds
Remove definition of _GCC_VERSION_AT_LEAST
Support icu provided by Windows
Fix comments from C++ to C/C++ in psl-make-dafsa
Replace psl2c by psl-make-dafsa
Simplify license headers