Support for unequal read lengths in BAM

[dboceck]

According to this closed issue #107 it is an expected behaviour for GangSTR to fail with an error if the aligned reads in the input BAM file have not all the same length.

Is it possible to include a flag to ignore this fact? Or is there another way how we could use GangSTR on a BAM file without reducing it to a subset of reads with a certain length?