#1307: Parsing crashes on unknown trait

If a class consumes a trait that is not known in the project then it is
represented as a string in the list of traits instead of a
TraitDescriptor.

The code that pulls in inherited methods and properties did not account
for that scenario and always tried to access the trait as if it was a
descriptor.

With this commit I have added a condition that the methods and
properties of a trait should only be inherited if it is a
TraitDescriptor. Tests are added to safeguard this behaviour.

In addition a 'loose' method in the test case was removed that served
no purpose.
#1213: Resolve @see and @link to Markdown link

In descriptions it is allowed to use the @see and @link tags; these tags
provide a link to a URL or other element in the project. In this commit
I have added a compiler pass that visits every description and replaces
the `@see` and `@link` tag with a Markdown-formatted link to that URL
or href.

I have chosen for a compiler pass because the transformer is the only
part that really knows the URLs for Descriptors and has a list of all
elements that are documented in the current project.
#1213: The var_dump is a lie
Removed unused file
Merge pull request #1314 from mvriel/feature/1213

#1213: Resolve @see and @link to Markdown link
@covers tag is incorrect
Merge pull request #1312 from mvriel/feature/1307

#1307: Parsing crashes on unknown trait
Merge branch 'develop' of github.com:phpDocumentor/phpDocumentor2 into feature/1267

Conflicts:
	src/phpDocumentor/Transformer/ServiceProvider.php