v0.9.3

First external contributions!

Impressive ChangeLog:

• Updates for ParaView-5.4.1
• New cmake structure, find_package(TTKBase) find_package(TTKVTK) now available
• New simple python, vtk-c++ and plain c++ examples (TTK companion paper teaser)
• Greatly accelerated merge tree features using task-based Fibonacci heaps
• Bottleneck and Wasserstein distances between peristence diagrams
• Lp distance between scalar fields
• boundary mask on scalar field critical points
• optional 3D embedding of the persistence diagram
• optional mask array for constrained smoothing
• bug fixes in DiscreteGradient
• bug fixes in TopologicalSimplification
• code cleaning