0.23.1
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
psl-make-dafsa: embed only the basename of the input file
Replace psl2c by psl-make-dafsa
Simplify license headers