Since the python part of the libproxy extension seems to be little used, I renamed the extension and dropped the python dependency - python remains an optional dependency.
Note also that libproxy depends on webkit, but since webkit depends on libproxy via glib-networking, I removed the webkit dependency from libproxy to avoid the circular recursive dependency.
Since it's difficult to be sure I caught all possible circular references, please report if the apps gui/tce-load halts unexpectedly for extensions using libproxy.