Merge pull request #2 from alchemyst/master

Updating repo
Sage versions of textbook examples

Two examples from the textbook, as well as some interactive tools built
some time ago to better understand transfer functions and their
relationship to the time domain
Solved example 7.7

Circle function in utils.py was also broken
Revert "Solved example 7.7"

This reverts commit b17ea29b23cbcf41c7a81e1036b4f699f03a6d49.
Solved example 7.7
Applied PEP8 to example 7.6
Merge pull request #78 from bsaaiman/master

Example 2.2, allowable delta's from page 262, two interactive transfer function examples
Merge pull request #79 from Fugacity59/master

Solved Example 7.7
Solved example 2.9
Merge pull request #80 from Fugacity59/master

Solved example 2.9
Merge pull request #2 from alchemyst/master

update