Merge pull request #317 from msgpack/fix/build-version Fix version of 1.0.1

Merge pull request #295 from msgpack/work/bump-version-1.0.0 Bump version 1.0.0

Merge pull request #276 from msgpack/fix/rc Prepare RC1 release

Fix net35 test build. 

Update changelog. 

Update change log. 

Merge pull request #256 from msgpack/fix/#252 I confirmed branch CI log shows "build succeeded" but never ends...

Fix release date. 

Merge pull request #250 from msgpack/wip/improve-packer-unpacker Improve packer unpacker performance

Fix nuspec.