A method 'density_matrix()' for evaluating a density matrix of a given shell
has been added to class ProjectorShell. It requires an ElectronicStructure
object as an input an by default produces a site- and spin-diagonal
part of the density matrix using the Fermi-weights obtained directly from VASP.
Ideally, this density matrix should coincide with the one calculated
within VASP itself (inside the LDA+U module).
Corresponding sanity test has been added, which shows only that the
calculation does not crash. Real numerical tests are needed.
When a ProjectorShell is created it creates a view of the full
projector array with orbital 'ilm' and band 'ib' indices interchanged.
The reason for this is that this corresponds more naturally to the
definition of the projector P_{m\nu} and also allows for multiplications
of projector matrices without additional transposition.
The tests have been modified accordingly.
A preliminary test suite for class 'ProjectorGroup' was added.
Currently, only a simplest test is performed testing that
after the input is processed the resulting projectors selected
within a given energy window are corret.
The problem was that when one shell was specified without an explicit
group the created automatic group was lacking the default values for
parameters 'normalize' and 'normion'. The current design, however,
assumes that they must always be set.
A single-file test suite for 'inpconf.py' is split into several files,
each containing a separate TestCase class. In addition, all test cases
are derived from class ArrayTestCase (in turn derived from TestCase)
which contains a numpy-array equality method.
