TRON-Bioinformatics/splice2neo: Release 0.4.0

This release covers:

• Leafcutterr: The strand information while leafcutter parsing is now retrieved from the cluster id in the count table.
• Spladder: previous code changes missed to consider the event type in generation of the junc id for alternative splice sites. This is fixed now.
• More tests were added
• An old bug in spladder_transform_mutex_exon was fixed
• Until now a junc_id could appear multiple times if it could be part of multiple events. As we are not interested in re-constructing the events, now unique junc_ids will be returned.