add ValidatorHelper.isAbstractOrHasEmptyConstructor()
allow abstract fragments to have any kind of constructors
remove unused method
Lazily generated SharedPref editor context field

This code changes eager field generation to lazy, so the context field
in SharedPref Editor classes is only generated if needed.
Fully lazy generate context field for SharedPref
Merge pull request #1031 from WonderCsabo/1030_lazyPrefEditorContextField

Lazily generated SharedPref editor context field
Merge pull request #1093 from dodgex/AllowConstructorsForAbstact

Implement #1081 (allow any constructors for EFragment)