Added NumPy examples for Craig's presentation

Example 1: algorithm for finding the pairwise distances between all spheres in a
set. Multiple functions are defined and benchmarked to show how to use
NumPy to maximum advantage.

Example 2: the distance-finding algorithm is used for collision detection
Added matplotlib examples

basic_matplotlib.py shows the simple pyplot interface
presentation_graphics.py illustrates more advanced plotting with
  the object-oriented API
plot_circles.py is another example used to make a figure for
  my presentation

Removed unneeded import in NumPy/distance_validation.py
Added matplotlib examples

basic_matplotlib.py shows the simple pyplot interface
presentation_graphics.py illustrates more advanced plotting with
  the object-oriented API
plot_circles.py is another example used to make a figure for
  my presentation

Removed unneeded import in NumPy/distance_validation.py
Added SciPy signal processing examples

SciPy/linear_filters.py
Demonstration of linear filtering with SciPy

SciPy/LTI_Simulation_with_Python.py
Modeling a 1st-order LTI system with SciPy
Added SciPy signal processing examples

SciPy/linear_filters.py
Demonstration of linear filtering with SciPy

SciPy/LTI_Simulation_with_Python.py
Modeling a 1st-order LTI system with SciPy
Merge branch 'master' of github.com:cfinch/OrlandoPythonUserGroup
Merge pull request #3 from cfinch/master

Adding files for Craig's NumPy/SciPy/matplotlib presentation