RGA subplot function and some pep8

Added a function to the existing RGA file that plots a subplot for each
element of the RGA matrix. Also changed some stuff in the file to be
pep8 compliant.
Reworked Example 2.3

Reworked Example 2.3 for transfer functions of any order
Merge remote-tracking branch 'upstream/master'
Merge pull request #63 from stelmo/master

Fixed the "sigh" commit error...
Merge remote-tracking branch 'upstream/master'
Added State Space zero function
Merge pull request #5 from alchemyst/master

Updating
Expanded utils and started on connect function

Corrected a few errors in utils
Made feedback function MIMO aware (cleared TODO)
Defined tf_feedback function to act on tf objects
Added tf_step function to plot steps response of transfer function
Added input and output names to tf object - to be replaced by line
objects in future
Added name field to tf object - feels this might be unnecessary but need
some way of referencing the name of an object (since the object has most
likely been assigned a name when it was defined there must be another
way...)
Defined __pow__ function for tf object to make writing tf's using s =
tf([1 0]) possible for transfer functions with repeated factors
Added simple omega convenience wrapper under utils
Demonstrate first MatLab reference example in connect
Defined basic classes that will be used to complete connect function and
tested basic structure
Connect function needs to be expanded but a skeleton has been created
Merge pull request #65 from SimonStreicher/master

Expanded utils and started on connect function
Removed unused distance_from_nominal function
Small formatting change
Merge branch 'master' of https://github.com/alchemyst/Skogestad-Python

Conflicts:
	utils.py
Applied Pythonic conventions for 'undefined'
Renamed feedback functions
This undoes the breakage introduced by making a new feedback function which didn't work as the old one did, breaking several working examples.
Pythonificiation of some changes
Merge pull request #1 from alchemyst/master

Updating repo
Sage version of Example 5.6

All in my quest to understand RHP zeros...
Merge pull request #66 from bsaaiman/master

Sage version of Example 5.6
Corrected state controllability function

Corrected the calculation of the input pole vectors
Revert "Corrected state controllability function"

This reverts commit 3d41aec796ae495aeceb94792d083c2c5a91a411.