Make PyLint ignore the import errors
Reduce loader load iterations and log shadowed modules

When loading module we process both the compiled and non compiled
versions of the same module. We now skip the compiled version of the
module if the non compiled version exists.

When an internal module is shadowed by a custom module we now log that
at the trace level.
Merge pull request #17207 from s0undt3ch/hotfix/custom-modules-shaddowing

Reduce loader load iterations and log shadowed modules
Merge branch '2014.7' into develop