tweak for 4.0 release
tweak
Updated Mojo name (antlr4) and default phase (generate-sources)
Use project source encoding setting by default
Do not require explicit setting of source and output directories
Updated Mojo documentation
Set inceptionYear, organization, and mailingLists; fix scm url
Fix url, specify reporting plugins
Prediction context documentation including graphs
Fix incorrect HTML excape in Javadoc code tag
Remove unused "true" and "false" templates
Use hard tab in code generation template
Update CHANGES.txt
Merge pull request #144 from sharwell/maven-and-javadoc-updates

Maven and javadoc updates
Fix Maven goal references
Use a template to fill in the correct version reference
Fix diagrams for ATNState documentation