Bumping version to 1.8.0
ReleaseNotes and news update.
Merge pull request #879 from dbabokin/v180

v1.8.0
Bumping version to 1.8.1dev
Merge pull request #880 from dbabokin/v180

Bumping version to 1.8.1dev
typos
Merge pull request #881 from dbabokin/typos

typos