merging p23 into master

examples/asc_test/master.py

examples/asc_test/master1.py

examples/asc_test/master1py

examples/asc_test/master2.py

examples/asc_test/master3.py

examples/asc_test/master3_plot.py

examples/asc_test/master4.py

examples/asc_test/master4_plot.py

examples/asc_test/master5.py

pykat/SIfloat.py

pykat/__init__.py

pykat/colours.py

pykat/commands.py

pykat/components.py

pykat/detectors.py

pykat/exceptions.py

pykat/finesse.py

pykat/node_network.py

pykat/param.py

pykat/plotting.py