adding intervaltree to manage gaps in topics to prevent OOM

[patkivikram]

This should fix #86

[codecov-commenter]

Codecov Report

Merging #282 (54fa365) into master (84302f5) will decrease coverage by 0.01%.
The diff coverage is 90.00%.

@@            Coverage Diff             @@
##           master     #282      +/-   ##
==========================================
- Coverage   94.71%   94.70%   -0.02%     
==========================================
  Files         100      100              
  Lines       10842    10851       +9     
  Branches     1481     1483       +2     
==========================================
+ Hits        10269    10276       +7     
  Misses        500      500              
- Partials       73       75       +2     

Impacted Files	Coverage Δ
faust/transport/consumer.py	94.31% <90.00%> (-0.27%)	⬇️

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[wbarnha]

Any particular reason why this hasn't been merged? It seems fairly useful. I don't know much about the intervaltree library but anything that stops failures for large partitions is welcomed.

[wbarnha]

Tested everything, looks good. I'll merge.