Add missing overrides for ModifierVisitorAdapter

[thejohnfreeman]

Closes #300

[ftomassetti]

It seems to not compile:

[ERROR] /home/travis/build/javaparser/javaparser/javaparser-core/src/main/java/com/github/javaparser/ast/visitor/ModifierVisitorAdapter.java:[804,12] cannot find symbol
  symbol:   class R
  location: class com.github.javaparser.ast.visitor.ModifierVisitorAdapter<A>

[ftomassetti]

I think it makes sense but we should fix the return type of the second method

[thejohnfreeman]

Yeah, sorry about that. I fixed that and tried to add a test. Let me know if it doesn't meet the standards or is in the wrong place. This is my first time using JBehave.

[coveralls]

Coverage decreased (-0.06%) to 61.172% when pulling fcf024f on thejohnfreeman:master into 9b239aa on javaparser:master.

[ftomassetti]

No problem, tests are there to help us catch these things :)

[ftomassetti]

I do not understand what this test is doing. It instantiate an object and then it verifies it is not null?

[thejohnfreeman]

Yes. The real test is that the construction compiles. If ModifierVisitorAdapter is missing any overrides like it was before this patch, then the construction will not compile. I added the assertion just so that the test has at least one. I'll make this test look however you want, just tell me.

[ftomassetti]

I would suggest we just remove the test and merge the change as it is.

Thanks for your help on this one!

[thejohnfreeman]

As you wish.

[coveralls]

Coverage decreased (-0.06%) to 61.172% when pulling 52dc8de on thejohnfreeman:master into 9b239aa on javaparser:master.

[ftomassetti]

Looks perfect. Thanks again!