Filter WSDL methods 

We already discuss this changes in #174. I fork branch from 3.x. Add additional tests. So, I'm waiting for response and review wishes.
Have you considered using one of the existing wsdls instead?

As I see it the primary purpose of this functional test case is to cover the changes to the `Generator` class. This could be done using [one of the simpler WSDLs](https://github.com/wsdl2phpgenerator/wsdl2phpgenerator/blob/master/tests/fixtures/wsdl/abstract/abstract.wsdl). This would make code generation a bit faster and reduce the number of fixtures.