Use strength_scale instead of fixed value for Blue-RedGreen strength
This should especially improve maps for Gaussian patterns, but also direction maps
Merge pull request #563 from Tobias-Fischer/lissom_fix

Allow Blue-RedGreen projection strength to vary with speed and dataset.
Added state_push/pop to ProjectionSheet to reset activities
Updated doc/reference_data submodule reference
Updated nbpublisher submodule reference
Updated doc/reference_data submodule reference
Added empty_storage_hook to analysis/__init__.py for use in topo profile

The use of lambda functions in notebook_setup.py was preventing
snapshots from being saved from the notebook environment.
Fixed CoordinateGrid SheetCoordinateSystem initialization
Updated dataviews submodule reference
Set default rows/cols to 11 in CFProjection.grid() to view central CF
Simplified grid method on CFProjection
Updated dataviews submodule reference
Updated imagen and featuremapper submodule references
Brought OpenMP documentation up to date
Updated param submodule reference
Updated som_retinotopy data for training tests

Python hash function (used when time_dependent=True) was found to be
platform specific. A new platform-independent hash has been implemented,
modifying the random streams and requiring new reference training data.
Updated param submodule reference
Reintroduced updated som_retinotopy.ty_DATA file for training tests
Updated dataviews, imagen and featuremapper submodule references
Updated all submodule references in external