sergio authored Jan 29, 2019 and Andrew Heather committed Dec 10, 2020

  - New solver: `acousticFoam`
  - New base finite-area region class: `regionFaModel`
  - New base shell model classes:
    - `vibrationShellModel`
    - `thermalShellModel`
  - New shell models:
    - A vibration-shell model: `KirchhoffShell`
    - A thermal-shell model: `thermalShell`
  - New finite-area/finite-volume boundary conditions:
    - `clampedPlate`
    - `timeVaryingFixedValue`
    - `acousticWaveTransmissive`
  - New base classes for `fvOption` of finite-area methods: `faOption`
  - New `faOption`s:
    - `contactHeatFluxSource`
    - `externalFileSource`
    - `externalHeatFluxSource`
    - `jouleHeatingSource`
  - New tutorial: `compressible/acousticFoam/obliqueAirJet`

Signed-off-by: Kutalmis Bercin <kutalmis.bercin@esi-group.com>