Several improvements and additions

• Chicken and duck alleles that were missing in IMGT, kindly provided by ZeZhong Li
• More control for overlapping reads in Checkout, better algorithm for overlap
• Ability to force MIG size threshold and collision filtering for all samples when running AssembleBatch
• Correct counting of MIGs when multiple files from the same sample are provided to CdrBlast
• Non-functional clonotype statistics reporting in FilterCdrBlastResults
• Minor fixes