[Leader] - complex nonlinear path generation

[buckbaskin]

implement the differential equation path generation for the Leader class. Key features:

• Departure (source)
• Arrival (sink)
• Traversal (linear)
• Distance based weighting
• Collective summing
• Motion model for translation from robot position/velocity to next step
• bring it all together.

Note: This issue should be closed and issues should be opened for each of the above bullets as the methods are added to the class.

[buckbaskin]

Issue closed and replaced with sub-level issues for different features.

34 #35 #36 #37 #38