New Imagen IPython extension to display PIL images (ipython.py)
Removed Id tags
Removed Id tags
IPython display module only imported when extension loaded
Simplified imagen IPython extension which now works with qtconsole.
Deleted trailing whitespace
Made a new abstract class TimeDependentValue for ExponentialDecay so that other time-dependent functions can be added easily
Removed unnecessary call to get_ipython()
Introduced concept of 'DataViews' in dataviews.py

DataViews allow patterns that have been instantiated from Imagen (such
as 2D Numpy arrays) to be annotated with the appropriate metadata
(such as the pattern bounds). Dataviews add general support for
storing time-varying patterns.
Added NumpyFile as numpy array image reader in image.py.
Added tests on scale and offset in PatternGenerator's __call__ before doings ops.