Revert "Added WIN32 specific directives and usblib include path"

This reverts commit 79324d886ca4fb02849c89414f5b020929325546.
VS2010 cleanup

Removed libusb 1.0.9 dependencies as it seems to be useless for Windows
OwlNest version and a more recent fork libusbx is available at
http://libusbx.org/.
Reverted dfu-util modifications because the original source code can be
found at http://dfu-util.gnumonks.org/. They also offer binaries for
Windows including the precompiled libusbx DLL file.
Added 96x96 size to icon.ico file and now compilation successfully
complete.