Fix bug in v1.2.0 and additional bug; Add more tests

• Fixes the bug in Writer that was introduced in v1.2.0. PR 19
• Fixes a bug in how LZ4 buffers are passed to LZ4_compress_fast_continue. This bug depends on the malloc implementation. It seems rare to be triggered using glibc on Linux, but common using malloc on Mac OS X. However, this bug could happen on all systems. PR 19, PR 27
• Fixes Reader to never return an negative byte count from Read. PR 20
• Removes an unused field from Writer and CompressReader. PR 28
• Updated tests to use python3. PR 15
• A variety of small fixes to the unit tests, including additional test coverage, and fixing the benchmarks so they run.

DO NOT USE: Require Go 1.17; Fix go vet SliceHeader warnings

DO NOT USE: This version introduced a bug, which is fixed in v1.3.0 / PR #19.

The original "fix" in this change is PR #17.

Add bounds checks to Uncompress(Alloc)Hdr

Previously these functions would panic. This makes them return an error instead.

v1.1.0

• Introduces new Readers, CompressReader and DecompressReader
• CompressReader provides an interface for passing an io.Reader for compression
  and returning an io.ReadCloser for reading the compressed data.
• DecompressReader mirrors the functionality of the existing Reader but with
  2x performance and fewer allocs. Reader is now deprecated in favor of this new type.

v1.0.3

• Writer now supports any input size, not just blocks smaller than 65 KB. PR 10
• Writer ensures the double buffer used for writing do not move in memory. PR 11

v1.0.2

Fix panic with read when provided a buffer smaller than the decompressed data. The new version buffers the inflated data for later read calls when this happens. PR 9

v1.0.1

Stop using deprecated LZ4 functions anymore.
This removes the warnings that show up during compilation.

The API or its behaviour remains unchanged.

v1.0.0

While this release does not break API compatibility, it changes the way the library is built.
Starting with this version, the C source code for liblz4 is not included in the Go package anymore.

The liblz4 needs to be provided externally, using a package manager or a manual, from source installation, for example.

Detection of liblz4 now relies on pkg-config to add the correct CFLAGS and LDFLAGS.

See README for instructions on how to install or build liblz4 externally.

Initial release

This version includes liblz4 source code version r131.