always set the conf variable in config library

it is needed when saving the settings from the GUI but previously
it was not set if the config does not exists thus the save fails
in this case
catch exceptions during config writing from GUI
add section if it does not exists when writing from GUI

this can cause runtime failures as if config does not exists and
only a few sections and options are added from the GUI the config
may be incomplete and the config module assumes that if the config
exists it is complete in terms of sections and options. deffineytly
something to look at in the future
added FIXME followup from the previous commit
just reload the config module when changing values from GUI (issue #79, again)