This puts the wxWidgets3.0 and libpng generated library files into the
deps folder, and puts the other builds files in a subdirectory from
where the project files are located. This is consistent with all the
other 3rdparty projects.
The output libraries for Devel builds are also suffixed with -dev
instead of -dbg now.
Move libpng out of wxWidgets 3.0 so it's available to other projects.
Delete libjpeg since there's a newer copy already available in 3rdparty
(still outdated though).
Jonathan Li