Improved merging

Update on merging:

• Improved insertion based merging taking the length into account
• Enabling distance to be a function of the length of the SVs
• Improved output including CIPOS CIEND and additional GT fields
• Tracking of VCF ID through merges
• Report merged sequence information
• Various improvements in output VCF file

Update on filter conversion:

• Bugfix in length threshold if SV len is different than breakpoint distances.