added zero direction calculation functionality
Example 4.9 and Exercises 4.6 + 4.7 done with sage
minor fixes with zero_directions
Merge pull request #48 from ibassa08/master

Applied PEP8
Merge pull request #3 from alchemyst/master

Updating
Merge pull request #47 from stelmo/master

Sage and python additions
Removed some unnecessary files
Merge branch 'master' of https://github.com/SimonStreicher/Skogestad-Python
Added a function to compute the condition number
Merge branch 'master' of git://github.com/ruanne/Skogestad-Python into ruanne-master
Get rid of plotting when we only want results
Autopep8
Merge branch 'master' of https://github.com/alchemyst/Skogestad-Python
Applied pep8 to Chapter_06.py
Renamed Example_04_04_Control_Toolbox.py
Applied pep8 to Chapter_05.py and deleted redundant versions

Files SISO_08rule.py and SISO_RULES.py are redundant compared to Chapter_05.py and have been deleted.

siso_controllability.py has the same aim as Chapter_05.py but utilizes the control toolbox.
Merge pull request #50 from SimonStreicher/master

Applied pep8 to Chapter_06.py and Chapter_05.py
Update plots and legends in Ch 2
Merge branch 'master' of git://github.com/Fugacity59/Skogestad-Python into Fugacity59-master

Conflicts:
	Example_02_10.py
Merge branch 'master' of https://github.com/alchemyst/Skogestad-Python
autopep8
Streamline controlability matrix calculation