Add functions for getting include paths and definitions for C/C++ projects

If the current file is associated with a supported project type, currently only
CEDET EDE, it is queried for associated include paths and definitions, if
available the proper command line arguments for Clang and cppcheck are
constructed.


This is an "almost" finished feature and I'm submitting the pull request mainly to get some code review. There aren't any test cases for the feature yet and the current solution for getting the source-file is a little hackish.