Allow multiple aliases per bean and add return type aliases

[codeliner]

Resolves #74

Implementation is very close to what we've discussed in the issue, except that I use a single @Alias for named and for return type aliases. It makes the implementation simpler ("aliases" attribute of bean can be a collection).

Like noted in the issue: the PR introduces a BC break

[coveralls]

Coverage increased (+0.3%) to 90.174% when pulling ac6ee89 on codeliner:feature/advanced_aliases into fefe256 on bitExpert:master.

[shochdoerfer]

PR looks good. 2 minor issues:

• What is the reason of not supporting native types as aliases? Sure, logically it does not make much sense, but is there a need for for this restriction? If so, it might be better to move the check to the Alias annotation class, that way we can be sure we deal with valid Aliases all the time.
• The exception which is thrown when a duplicate alias exists should also contain the method name. IIRC this is stored in $aliases[$alias]. That should help when it comes to debugging.

[codeliner]

@shochdoerfer Reason was that it does not make much sense ;) But you're right user can take care of it. And if a user wants to use "array" as service id (why ever ...) we can allow it. Simplifies the code 👍

Also good hint with including the method name. Added it to exception message.

[coveralls]

Coverage increased (+0.2%) to 90.064% when pulling 251d9a0 on codeliner:feature/advanced_aliases into fefe256 on bitExpert:master.

[shochdoerfer]

...and merged. Thanks @codeliner for your contribution. Will release the next version soonish but first want to refactor the parameter handling as well.