Functionality for removing key from LSH index

• Add remove method for LSH index - lsh.remove(key)
• Add membership check for LSH - key in lsh

Introduce Weighted MinHash and interface change

• Add Weighted MinHash data sketch
• Add Weighted MinHash LSH index
• Performance and accuracy benchmark for Weighted MinHash
• Rename digest to update for MinHash and HyperLogLog, and use bytes as input argument.
• Make hashobj customizable through data sketch constructors
• Add new methods for data sketches
• Bug fixes