import leo.core. leoGlobals as g in most files in leo.plugins.importers.
leoImport.py appears to work with new_importers switch set to True.  But for this commit, it is set to False.
Simplified g.importFromPath.  The first argument must be a simple (no dots) module name. The second must be a path containing the .py file for the module.
Updated unit tests for recent changes, including code that examines leoImport.new_importers.  All tests pass.