When using checkPythonSourceCode integrated in the source code editor,
for a scenario where developer edit a component and save we can benefit
from caching the check message for the source code content, because the
same check that the one happening in the editor will happen when the
component is saved.

This cache varies on:
 - "component_packages" cache cookie which is reset every time some
component code is edited.
 - zope startup time to take into account editions of file system code.
This assumes that after reseting file system code zope will be
restarted.
 - portal_type, because the checks performed by this function also
depend on portal type.