BibSched: more customizable icon creation tasklet

• Added parameter 'icon_format_mappings' to define the format of the created icons for each source file format. Defaults to newly introduced CFG_ICON_CREATION_FORMAT_MAPPINGS.

• Added parameter 'docnames' to choose for which BibDoc the icons should be created

• Added parameter 'add_default_icon' to mimic the traditional behaviour of WebSubmit when adding default gif icon.

• Added parameter 'inherit_moreinfo' for created icons to inherit the comment and description values of the source BibDoc.

Signed-off-by: Jerome Caffaro <jerome.caffaro@cern.ch>
Acked-by: Ludmila Marian <ludmila.marian@cern.ch>