v19.3.0

Fix

• SimulationActor produces negative MaterialSlab thickness (#1288) (75f0835) (@andiwand)
• Add another compat fix for clang+libstdc++ (#1269) (4a21df3) (@paulgessinger)
• Add missing dependency in Exa.TrkX plugin (#1276) (baa4222) (@benjaminhuth)

Refactor

• Python examples vertex_fitting.py (#1286) (c586094) (@andiwand)
• Move propagator options to general fitter options (#1282) (bf8cb1c) (@osbornjd)

CI

• Bump ccache max size to 500MB (#1285) (e6e7949) (@paulgessinger)
• Retry nodeps build if it fails the first time (#1283) (93c608d) (@paulgessinger)
• Reduce ccache limit to 150MB (#1270) (9920a81) (@paulgessinger)

Feature

• Add Profiling Support with gperftools (#1274) (7bf3981) (@Scott-James-Hurley)