added np_ext.argsort_split() a new magic function to subdivide arrays in monotonically increasing subsets.
now VariantCallSupport is directly loaded by proxy.py
removed pleonastic operation.
Simpified interface to genomics.create_markers_array.

Dropped the requirement for an explicitly assigned 'op_vid' in the
input markers definition stream.
added one more unit test
now all variant_call_support functions are available via kb.genomics
Added genomics.create_vcs().

This function will create a vcs starting from a Markers array and a
positions record array, typically generated by aligning the marker's
masks to a given reference genome.
Added VariantCallSupport.get_multiple_origins_nodes(self)

Retrieve all nodes with more than one origin and a count
of how many origins there are for each node.
Merge branch 'mset_to_vcs' into develop

Added a new function to build a vcs from a markers array (and a
reference_genome and alignment position info).
Precleaning support in objects deletion.

KB assures that an object on which other objects depend cannot be
cancelled. On the other hand, there are object of special types, e.g.,
DataObject, on which other objects cannot depend and should be deleted
when the master object, e.g., DataSample, is deleted.

To simplify handling of the latter case, I have added
proxy_core.__precleanup__(),  a method that is invoked, before
anything else, by kb.delete(obj).
Merge branch 'precleanup' into develop
fixed kb.delete(vcs) bug
Merge branch 'fix-vcs-bug' into develop
bug fix: vcs._clone_structure() was not changing vid.
Ipython notebook based examples

Added basic infrastructure for example writing based on ipython
notebooks. The idea is to write the biobank examples directly as
notebooks and to generate 'static' documentation by converting the
notebooks into rst. It is expected that this will simplify the tedious
task of writing example code and maintaining it in phase with
development.

The makefile notebooks/Makefile has a ipynb to rst conversion
as its default target, while  'make startnb' will start a, local,
ipython notebook server.
Ipython should be version 1.1 or above.
added README
Added basic vcs creation example.
Added basic vcs operations example.
Merge branch 'notebooks' into develop
added an example notebook on creating a VCS from a VCF file.