Example applications

[DanielVandH]

Could be good to use some proper examples focused on applications, especially as a way to show how the interfaces should be used in a clearer way. For example:

• Using my other package FiniteVolumeMethod.jl, demonstrate adaptive mesh refinement, using a posteriori error estimates to impose area constraints on each triangular element iteratively.
• Demonstrate a cell simulation model which uses Delaunay triangulations and Voronoi tessellations to model cell connectivities and Voronoi polygons to model geometric properties of a cell (i.e. area).
• Image compression with Lloyd's algorithm.

[DanielVandH]

Closing this as it is mentioned already now in #63 and is already in progress in the new-docs branch.