date_format renamed to date to match Jtwig.
Fixed broken tests
Added render context unit test
Added tests to cover jtwig-core missed branches.
Merge pull request #176 from lyncodev/general-tidy-up

General tidy up
[maven-release-plugin] prepare release jtwig-3.0.0
[maven-release-plugin] prepare for next development iteration
Merge pull request #175 from lyncodev/date-format-function-rename

date_format renamed to date to match Jtwig.