overload Write() for char and unsigned char too, otherwise code writing them fails...

overload Write() for char and unsigned char too, otherwise code writing them fails due to lack of exact match and absence of overloaded wxToString()

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@54252 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775