Remove the Perl modules composing upmake from wxWidgets repository, it's too
difficult to maintain them both here and at https://github.com/vadz/upmake and
just keep the wxWidgets-specific upmake_script.pl here and generate
build/upmake_script itself from it using fatpack.
This also updates upmake to the latest 0.3 version, as a side effect.
Use slashes, not backslashes, in the paths.
Use "auto" for all text files under docs/msw as all of them could be opened in
Notepad.
Also use Unix EOLs for configure.in (and not just for configure).
