removing old testCases/ directory, to follow numpy/scipy testing convention
removed unnecassary test case file, and updated MANIFEST
Implemented impedance and admittance parameters.

As far as I could tell, the impedance and admittance parameter support was more of
a place holder.  I've implemented s2y, y2s, s2z, z2s, y2z, and z2y using the matrix
algebra support in numpy.

Note that s2y, y2s, s2z, and z2s require an additional z0 parameter (scalar or 2d
array).

Thanks for all of the work you've put into this very nice module.   -- Trey
Fixed bug which prevented complex values for y and z parameters.
Adding to plotting.smith() a MATLAB-like smith chart option
Merge pull request #4 from treygreer/master

Impedance and Admittance implementation  (with tests)
Merge branch 'master' of github.com:scikit-rf/scikit-rf
Merge branch 'master' into develop

Conflicts:
	skrf/testCases/testNetwork.py
removed old testCases/ dir again. moved modified testNetwork.py
to tests/test_network.py
added a skip decorator to the rectangular waveguide test, because
i know it fails (due to z0, and port impedance mismatch? i forgot)

would like to skip methods in network.py starting with test_* that
arent tests, but i dont know how
modified README
moved 'z' and 'y' creation, to the accessing properties, as opposed to
the assignment of 's'. this was done to increase speed as
the s2y, s2z functions are slow.

ideally, all properties should be equal, an the user should be able
to set any of them. this will require a bit of re-design, will have
to get to it later.
Merge branch 'master' of github.com:scikit-rf/scikit-rf into develop
fixed bug in networkSet.signature.

hacked both Network and touchstone class to handle file-objects
as well as file-names. this should be re-done in a more coherent
way.
added class method of NetworkSet.from_zip() which will
take a zipfile of touchstones and return a NetworkSet, of the
files.
modified new NetworkSet.from_zip() to skip over files in archive,
which fail to construct a network .
added some more versitile functionality to the NetworkSet.signature(),
so that the difference can be any operation (div, sub, etc), and
allowed specification of difference from mean, or from initial
network
added a __len__() to network which return lenght of frequency axis.

added a convenience function to read in hfss gamma,z0 comments
and return an array of the data, and added a function which
returns a Media object. this can be used to de-embed the ports
on a touchstone.

currently , its just one-port support. need to add support for multi-port
added shunt_capacitor and shunt_inductor construction tests, because
they dont work!
made a fix to media.load, which should work for number-like or
array-like input.

fixed a new bug in calibration.apply_cal() that was introduced by
giving Network a __len__ property