Remove some unnecessary uses of 'pycore' in favor of 'project'.

Remove some unnecessary attributes.
Move 'pycore.modname' into libutils because it doesn't use pycore functions.
Move method to function because it doesn't use 'self'.

Move some methods from pycore to project.

These functions are better placed in the project object. Adjust the
functions that call them appropriately.

Use project, not pycore.

Move more methods from pycore to project.

These methods use objects from project and don't really have a reason
for being in pycore.

Use 'project.get_pymodule' instead of 'pycore.resource_to_pyobject'.
Have deprecated functions in pycore call replacement functions.
Merge branch 'upstream-6' of https://github.com/gwelymernans/rope into upstream-6