filterwheel.py -- filter editing working

One can now edit the filters OK.
global.py -- moved some former config parameters

HTTP_PATH_GET etc never change, and should not be allowed to, hence this.
usdriver.conf -- withdrawn

The code now comes with its own config parameters.
drivers.py, uspec.py, config.py, usdriver.py -- changed the configuration stuff

New separate sub-module to handle the configuration. Default defined within the code used if no file found. Saved at end of GUI; re-loaded at next start up.