Recommendation is to avoid using the year nomenclature as this
information is already encoded in the git repo. Avoids needing to
repeatly update.
Also updates AUTHORS.txt from current repo with contributor names
wxWidgets 3.1 has deprecated wxPATH_NORM_ALL when normalizing file
paths when calling wxFileName::Normalize(). This change keeps the
existing behavior except in places where our own internal
ExpandEnvVarSubstitutions() to expand environment variables.
The same logic block to resolve possible symlinks exists in 5 different
places now. This change moves this duplicated code to a static member
function of WX_FILENAME instead.
