fix: TypeFactory type arguments of constants

[pvojtechovsky]

needed by #1686

[spoon-bot]

Detected changes by Revapi: 4.

Old API: fr.inria.gforge.spoon:spoon-core:jar:6.2.0-20171231.234703-14

New API: fr.inria.gforge.spoon:spoon-core:jar:6.2.0-SNAPSHOT

Name	Change 1
Old	method TypeFactory::dateType()
New	method TypeFactory::dateType()
Code	java.method.returnTypeTypeParametersChanged
Description	The return type changed from 'spoon.reflect.reference.CtTypeReference<?>' to 'spoon.reflect.reference.CtTypeReference<java.util.Date>'.
Breaking	binary: non_breaking

Name	Change 2
Old	method TypeFactory::objectType()
New	method TypeFactory::objectType()
Code	java.method.returnTypeTypeParametersChanged
Description	The return type changed from 'spoon.reflect.reference.CtTypeReference<?>' to 'spoon.reflect.reference.CtTypeReference<java.lang.Object>'.
Breaking	binary: non_breaking

Name	Change 3
Old	method TypeFactory::shortPrimitiveType()
New	method TypeFactory::shortPrimitiveType()
Code	java.method.returnTypeTypeParametersChanged
Description	The return type changed from 'spoon.reflect.reference.CtTypeReference<?>' to 'spoon.reflect.reference.CtTypeReference<java.lang.Short>'.
Breaking	binary: non_breaking

Name	Change 4
Old	method TypeFactory::shortType()
New	method TypeFactory::shortType()
Code	java.method.returnTypeTypeParametersChanged
Description	The return type changed from 'spoon.reflect.reference.CtTypeReference<?>' to 'spoon.reflect.reference.CtTypeReference<java.lang.Short>'.
Breaking	binary: non_breaking

[monperrus]

Thanks a lot for this first 2018 commit!

Happy new year!

[pvojtechovsky]

Happy new year to you too ;-) I started to clean #1686. I will create about 12 small pull requests soon.