Simplify import/export (filter) configuration

[westram]

• Allow to edit filters from import/export dialogs
  • creating a copy of a filter should be possible
    (copy will be saved -locally; as implemented by #263)
  • attempting to modify a filter in $ARBHOME/lib/… should check read-only state of filter file and warn if set.
• Display filter result during edit
  • while editing the filter file, ARB shall check whether it was saved
  • after each save, display the "result" of the filter, i.e.
    • any error (e.g. if syntax is wrong)
    • in case of export: export the currently selected species and show the resulting output in a textwindow
    • in case of import: from the file selected in the main import window, import one or all species (into a tmp ) and display results (e.g. list of species, list of fields+contents for first/selected species)
• Add a description field to import/export filters
  • store in filter file (e.g. as DESCRIPTION line(s))
  • show description of selected filter in a small text field in import/export dialog (similar to comment in admin window)
  • changing the field content should update the description stored in the file (will not be possible if file is read-only, maybe make text-field insensitive in that case) skipped, not really useful

[westram]

Milestone renamed

[westram]

by [16564]