Update WSDG win32/win64 quick start guide to include dependencies and
instructions for building QtShark; note alternate cygwin package for
'patch' utility; update example setup script to add Qt bin directory to PATH,
and extract out paths as variables.

Change-Id: Id404b8757dbfd0dc1119b89e01bbe2fa139e2b38
Reviewed-on: https://code.wireshark.org/review/2751
Reviewed-by: Evan Huus <eapache@gmail.com>
Reviewed-by: Anders Broman <a.broman58@gmail.com>