Add a bit more to setup metadata.
Create next release branch.

- Development occurs mostly in: `development`.  Other development
  branches may be issued.

- Integration from development occurs in this branch from development
  branches that are stable to be included in the next release.

- Documentation review, version jumps and pre-releases occur in this
  branch only.  Notice this entails that checking version dependencies
  for releases also must be done in this branch only.
Remove out-dated HISTORY file.
Change README extension to match format.
Update copyright years.
Merge branch 'develop' into release-1.6
Integrate `xoutil.bound` into the release 1.6.3.
Fixes bound documentation.
Release 1.6.3.