removing python 2.7 test, shouldn't be changing it to support 2.7 anymore. Adding more recent python version

actually fixed the bug in the zero locks printing

See merge request finesse/pykat!15

Fixed a bug in the verbose output (it gave TypeError: 'float' object is not subscriptable)

See merge request finesse/pykat!14

Issue in setRTL where if a componant
was previously specified as `m`
and L and T are set, R
would not be overriden and
so would result in an error

beamTrace and plot_beam_trace are two
beam tracing algorithms which use different
methods to compute the beam trace.

Here I update the docs so these point to one
another

pykat.kat.beamTrace was defaulting to 1.064um
wavelenght when producing a beam trace.

This was likley a bug. I have updated the
code so the wavelength is preserved. Some results
for a simple telescope match my analytics
and also match a Finesse simulation with a
`bp` detector placed at several nodes.

Tested at 2um wavelenght.

Catch stderr from 'kat -v ' and 'kat -h' commands to ensure we catch dynamic library errors

See merge request finesse/pykat!13

There was a bug introduced in 3753e703
were setting fx and fy using the pykat interface
resulted in an error. This has been fixed and
unit testing added