* fix ASTVariableReference::value: correctly get reference value type
by using either initialiser of bindingTarget (broken since a codemodel
update in 2018)
* disable warning for casting in bool to null comparison (it does not
cast, is always false)
* fix property checks (where skipped without default of readonly)
* remove non relevant checks (ErrInvalidPropertyType for lowercase now that custom
value types are supported, and for properties called data)
* updated import version
Change-Id: I38407acf327d0f773b38dda4c02fb4d95a420851
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>
