This enables the user to unset the completion script path.

 - introduce a new parameter to force interaction (e.g. to save files)
 - default to be interactive in manual mode because it makes no sense otherwise
 - avoid interaction in other modes unless forced

Since the appender is defined in logger.conf and thus loaded by all
applications we need to remove it at load time from all applications
but the CLI EE tool.

Move code from FIJITestsViewer and generify it to make it usable for
other modules like the EE CLI tool.

Move code from FIJITestsViewer and generify it to make it usable for
other modules like the EE CLI tool.

Also, change shortcut for clearing the log to alt+c as implied by its label.

I.e. fix the chaos that has been growing for a while and the bugs
introduced in the patch
"fiji_ee_gui: allow to abort test runs even during long transfers"

 - make all of them a function
 - use the same parameter and return scheme for said function
 - unify indentation, wording and parameter names
 - document verbosity parameter

 - work correctly with new worker error mechanism
 - add endtime parameter
 - reorganize for better readability and less line breaks in output
 - use MIME::Lite to support SMTP servers with passwords

E.g., [cycles]

 - ROText and its master will stay active (to ensure logging works)

ConfigSpecs of type METHOD should point to setter/getter methods.
If given no argument they should return the previous value.
However, some of our methods do not follow this API and hence
break things when called as getters (w/o arguments). Most of them
are not used anyway so get rid of them and fix the others.

Unlikely to cause really problems but recommended.

We cannot estimate the necessary timeout if the test sequence uses
any triggers outside FIJI's control. Thus we have to wait forever (or
till the user aborts) in that case.