Use wxConvAuto in wxFile::Write().

For consistency with wxFFile.

No real change, as wxConvAuto will default to UTF-8 when writing.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@74434 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
Use wxConvAuto() in wxStyledTextCtrl::DoLoadFile().

This is both more reasonable than the current runtime encoding (the
input file is from unknown source) and more robust (it can handle UTF-*
encoded files transparently).

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@74435 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775