ENH: Use Python logging framework for scripted module logging

Use Python's built-in logging module to manage logging. A direct advantage is that line number, file name, method name can be logged, too. Also, it follows the convention of using qt-style logging in qt classes, vtk-style logging in vtk classes, etc.

Default behavior of log levels:
 DEBUG: log to application log only, includes file name, line number, thread
 INFO: log to stdout (appears in application log, too)
 WARNING: log to stderr (appears in application log, too)
 ERROR: log to stderr (appears in application log, too)

Usage:
 import logging

 [...]

 logging.debug("this is a debug message")
 logging.info("this is an info message")
 logging.warning("this is a warning message")
 logging.error("this is a error message")

From: Andras Lasso <lasso@queensu.ca>

git-svn-id: http://svn.slicer.org/Slicer4/trunk@23828 3bd1e089-480b-0410-8dfb-8563597acbee