Create tag REL_3.1.9

Bump version number to 3.1.8

Release against the most recent Eclipse release first

Create tag REL_3.1.6

Update Tooling API to 6.8

Create tag REL_3.1.4

Create tag REL_3.1.3

Create tag REL_3.1.2

Create tag REL_3.1.1

Create tag REL_3.1.0