Use canMergeChunks for of index blocks calculation to avoid too large of blocks

[cmdcolin]

This adds the canMergeBlocks from bam-js to tabix to avoid too large of blocks being downloaded

[codecov]

Codecov Report

Merging #121 (91b54c7) into master (962e5b4) will decrease coverage by 0.72%.
The diff coverage is 97.29%.

@@            Coverage Diff             @@
##           master     #121      +/-   ##
==========================================
- Coverage   90.74%   90.01%   -0.73%     
==========================================
  Files           7        7              
  Lines         551      531      -20     
  Branches      150      147       -3     
==========================================
- Hits          500      478      -22     
- Misses         51       53       +2     

Impacted Files	Coverage Δ
src/csi.ts	92.36% <94.44%> (+0.15%)	⬆️
src/tbi.ts	96.82% <96.77%> (-1.15%)	⬇️
src/util.ts	76.19% <100.00%> (+35.01%)	⬆️
src/chunk.ts	72.22% <0.00%> (-16.67%)	⬇️

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[cmdcolin]

Fixes #118

[rbuels]

Any reason this is still draft?

[cmdcolin]

I make everything draft by default currently

[cmdcolin]

It is probably good to go here though