IDEA-104677 Selected completion item isn't inserted by typing a colon
FileTemplatesTest -> groovy
FileTemplatesTest: test collect undefined attribute names
IDEA-110995 Custom variables dialog does not appear for included templates.
first draft of RunConfigurationProducer API
working version of RunConfigurationProducer API
ApplicationConfigurationProducer converted to new API
converting JUnit run configuration producer to new API (work in progress, doesn't compile yet)
JUnit producers converted to new API
document RunConfigurationProducer
use more explicit API
javadocs and some nullability
javadocs for RunConfigurationExtensionBase