Checker Framework

A generic framework should be created which provides the foundation for other plugins to report errors. Right now we have the problems toolview but it is tightly coupled to the DUChain. This should be changed to use a separate item repository which stores the problems for a given path. The data stored would be: Path and range of where the issue is found, a short error message and optionally a long description. Furthermore, plugins might want to store additional info from which the problem could be fixed (compare to the 'add include path' or similar wizards we have already in the language framework).

This framework should then be used to integrate various tools.

First of all the existing language plugins should show the problems they find there.
The existing playground plugins for krazy and cppcheck integration should reuse that framework
any other linters could be integrated, such as jslint, pylint etc. pp.
runtime checkers could be integrated, such as valgrind's memcheck, ptrcheck, helgrind, drd, ...