Improve timestamp/gorilla compression/decompression engine

[andreheringer]

There are a couple of improvements demonstrated by Michael Baum in hes teases. Namely:

• Increase maximum delta storage size from 14 bits to 32 bits (Baum uses 27, but I feel like 32 will be fine), in order to support millisecond precision.
• Increase the number of bits dedicated to encode the number of leading zeros in value compression from 5 to 6
• Use ZigZag encoding and reduce the value by one to reduce branch prediction
• Implement a first-order DFCM predictor

Baum implementation for reference here