Remove unnecessary nil checks

These nil-pointer checks were ineffective (the pointer would be dereferenced anyway) and unnecessary (the function is never called with a nil value for that parameter).

Pathfinder: improve cost calculation, and use it in NewWriterV2

Encoder: check for empty block

Fixes #51

Make my matchfinder work more accessible.

remove Content-Type requirement

* golang/go#31753 is fixed

Reader.Reset: recover from errors.

When a Reader encounters an error, its internal state may be corrupted.
So Reset needs to be extra thorough, to avoid cascading errors.

Based on PR 37 by Sovianum.

Optimize log2FloorNonZero with math/bits.

Retract v1.0.1

Revert "Faster bit writing."

This reverts commit c3da72a.

With the sample data from issue 22, one byte in the output file is zero
instead of the correct value. For now at least, we'll go back to the old
way of writing bits.

Fixes #22

Add documentation link.

Fixes #16