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 remote-tracking branch 'upstream/master'
Merge remote-tracking branch 'upstream/master'
Merge remote-tracking branch 'upstream/master'
Merge remote-tracking branch 'upstream/master'
Solved example 7.6
Merge remote-tracking branch 'upstream/master'
Merge pull request #75 from Fugacity59/master

Solved example 7.6