COMSOL interface & combined wave/GA simulation

Changes

Introducing classes that represent input data for sound field simulations
- itaSource
- itaReceiver
- itaMaterial
Introducing Comsol interface
- has a set of classes to represent a Comsol model tree
- allows to apply changes to a Comsol model that are specific for acoustic simulations
- works with input data classes mentioned above
- Also allows to
  - start simulations
  - read/import results in ita formats
  - ...
Introduced new functions in Kernel/DSP
- ita_interpolate_spk_result: Interpolates an itaResult in the frequency domain
- ita_result2audio_spk: Converts an itaResult to itaAudio using an interpolation in the frequency domain
Introduced classes for 3D model visualization
- AC3D
- Comsol models
Raven
- added function to set Material path
- bugfix with paths using Mac

Edited May 08, 2019 by Philipp Schäfer