feat: CtPackageDeclaration

[pvojtechovsky]

This is new Spoon model element, which represents package declaration - the line at top of compilation unit. Example:

package your.nice.package.name;
...

It is needed to complete #2702 ... and at the sniper mode of compilation unit header.

Actually it is not used in CompilationUnit. I plan to add it to compilation unit in PR #2702, which changes CompilationUnit a lot so it makes no sense to add it now.

[spoon-bot]

API changes: 4 (Detected by Revapi)

Old API: fr.inria.gforge.spoon:spoon-core:jar:7.2.0-20181020.225215-41 / New API: fr.inria.gforge.spoon:spoon-core:jar:7.2.0-SNAPSHOT

	Method was added to an interface.
Old	none
New	method CoreFactory#createPackageDeclaration()
Breaking	binary: non_breaking,

	Method was added to an interface.
Old	none
New	method Factory#createPackageDeclaration(String)
Breaking	binary: non_breaking,

	Method was added to an interface.
Old	none
New	method Factory#createPackageDeclaration(CtPackageReference)
Breaking	binary: non_breaking,

	Method was added to an interface.
Old	none
New	method CtVisitor#visitCtPackageDeclaration(CtPackageDeclaration)
Breaking	binary: non_breaking,

[pvojtechovsky]

needs merge of #2706 first to pass tests

[pvojtechovsky]

I rebased on master. Now the test should pass. It is ready for review.

[monperrus]

LGTM. We need the corresponding tests to specify this new metamodel concept.

[pvojtechovsky]

This metamodel concept is used nowhere yet. It will be used in new CtCompilationUnit (PR #2702). So till then it is hard to test it.
It already pass all existing general API tests about parent/child and collection handling, etc.

I have no idea actually what else we should test here.

[pvojtechovsky]

I made this PR as a minimal baby step, which adds new metamodel element, which is needed by already big enough #2702

[monperrus]

Can we create the node in JDTTreeBuilder in this PR? Then we can test the presence of the node and the pretty-printing.

[pvojtechovsky]

It makes this PR more complicated ... (less baby)

• I have to modify CompilationUnit and to add there code, which will be again removed in feat: CtPackageDeclaration #2707 ... so it is wasting of effort.
• I have to learn and modify JDTTreeBuilder (so I would need more time for that) - I would like to have it as the last step - first we need a model and then we can fill it in and use it.

... therefore less compatible with #2707, which is the main purpose of this PR.

[monperrus]

I understand.

48 of 66 new or added lines in 13 files covered. (72.73%)

We can live with that :-)