Meaningful names for benchmark scenarios

[charlesbmi]

Issue

Scenarios provide a convenient structure to describe the environment, transducers, and sensors. A collection of preconfigured scenarios are provided with NDK, and can be easily loaded.

The existing scenarios are:

SCENARIO_0 (2D) - a simple quickstart toy scenario that enables users to dive in and experiment with their first simulation immediately.
SCENARIO_1_3D (3D) - a scenario containing a flat 3-layer bone covered by skin, with water above the skin and brain below the bone. This is based on benchmark 4 of Jean-Francois Aubry, et al..
SCENARIO_2_3D (3D) - a scenario containing a full skull and brain mesh immersed in water. This is based on benchmark 8 of Jean-Francois Aubry, et al..
SCENARIO_1_2D (2D) - a 2D version of scenario 1.
SCENARIO_2_2D (2D) - a 2D version of scenario 2.

The scenario numbering does not correspond to anything meaningful. Instead, it would be helpful for users if we named them with descriptive names, like "3-layer skull model" and "RealisticSkull"

[charlesbmi]

Proposed naming:

• SCENARIO_0 -> ScenarioSimple
• SCENARIO_1 -> ScenarioFlatSkull
• SCENARIO_2 -> ScenarioRealisticSkull
• SCENARIO_3 -> ScenarioUltrasoundPhantom

[charlesbmi]

Open to suggestions whether these scenario names should still include their indexing, e.g. Scenario_0_Simple - this would keep their order in a file explorer / Github browser when viewing.