[*] Refactoring

[IAmNotHanni]

Another day another refactoring.

[IceflowRE]

The includes should be correctly ordered:

In dir/foo.cc or dir/foo_test.cc, whose main purpose is to implement or test the stuff in dir2/foo2.h, order your includes as follows:

    dir2/foo2.h.
    A blank line
    C system headers, and any other headers in angle brackets with the .h extension, e.g., <unistd.h>, <stdlib.h>, <Python.h>.
    A blank line
    C++ standard library headers (without file extension), e.g., <algorithm>, <cstddef>.
    A blank line
    Other libraries' .h files.
    A blank line
    Your project's .h files.

From Google C++ guidelines.

The code currently is not following any order completely.

[IAmNotHanni]

I will close this since we will merge rendergraph2 in the other PR now.