LZ77 interval speedups. Faster, smaller, simpler.
LZ77 interval speedups. Faster, smaller, simpler.

The initial re-writing of this part of the code with intervals
had to be done with a complex logic (mostly intervals with a
lower and upper bound, not a constant value like now) to properly
deal with the inefficiencies of the then LZ77 algorithm.
The improvements made to LZ77 since, now allow for a simpler logic.

There were also small errors in the interval insertion logic
that lead to small inefficiencies (hence a slightly better
compression rate).

Change-Id: If079a0cafaae7be8e3f253485d9015a7177cf973

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