Release v0.14

[ranocha]

To be included

• Make SaveSolutionCallback immutable #2640
• set_zero! instead of reset_du #2670

To be decided

• Unify boundary condition specification #1510
• Unify signatures of mesh constructors #1194
• Discuss names of serial/parallel mesh types #1046
• wrap RHS to reduce latency with OrdinaryDiffEq.jl #1255
  • If we want this to work smoothly, we will have to break plot(sol)

Postponed to later

• In-situ visualization #0: Make Makie available in 2D VisualizationCallback #2225

[DanielDoehring]

The changes to SaveSolutionCallback are somewhat breaking #2640