[DEV] UFEM: DNS particle Coagulation kernel
[DEV] UFEM: Checkpoint particle collision in Burgers vortex
[FIX] UFEM: Gradient IC initialization
[ENH] UFEM: Collsion kernel also works in 2D
[ENH] UFEM: Particle concentration discontinuity capturing
[DEV] UFEM: Discontinuity fixes
[DEV] UFEM: Further discontinuity tweaks
[ENH] UFEM: Initialize Semi-implicit from implicit
[ENH] UFEM: Brownian motion for particles and fix

Attempted fix for NaN when 0 particle concentration
[ENH] UFEM: Combined Brownian and DNS collision kernel
[FIX] UFEM: NaN problems
[FIX] Pressure statistics and output precision
[ENH] Add GenerateLine3D component
[FIX] Missing files
Merge remote-tracking branch 'barche/master'