Rename Lamb-Oseen like vortex implementation to Decaying vortex

Fix typos in generatePIVImages.m function docs

Refactor theoretical flow field image export to make it simpler

RankineVortexAndUniformFlow: Simplify generalize parameterization to allow definition of the constant velocity u,v components from a ratio of max. velocity magnitude

RankineVortexAndUniformFlow: Generalize parameterization to allow definition of the constant velocity u,v components from a ratio of max. velocity magnitude

Update changelog vor version 1.1.0

Clean-up code, simplify image generation configurations and improve improve error handling

Clean up code for Lamb-Oseen vortex implementation

Improve error handling for invalid flow types

Fix velocity normalization factor computation and cleanup the code

Plumb in sample Shear flows and sample Lamb-Oseen vortex flow

Clean up code and fix vortex center position for Rankine Vortex flow

New flow type: Shear flow

New flow type: Lamb-Oseen vortex

Create initial changelog and copy LICENSE to LICENSE.txt