add indel

[ericloud]

Some modification to manage indel as a specific case of SequenceInsertion or SequenceDeletion.

[codecov-io]

Codecov Report

Merging #46 into bloody will decrease coverage by 0.09%.
The diff coverage is 40%.

@@            Coverage Diff            @@
##           bloody      #46     +/-   ##
=========================================
- Coverage   59.66%   59.57%   -0.1%     
=========================================
  Files          29       29             
  Lines        2737     2748     +11     
=========================================
+ Hits         1633     1637      +4     
- Misses       1104     1111      +7

Impacted Files	Coverage Δ
pyGeno/Chromosome.py	79.09% <40%> (-4.25%)	⬇️
pyGeno/SNPFiltering.py	75% <40%> (-0.41%)	⬇️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 2b92517...ceb0ba5. Read the comment docs.