Sediment code cleanup

[SouthEndMusic]

Issue addressed

Fixes #745, split out from #735.

Explanation

Some of the changes include:

• Defining global constants for code clarity
• Avoiding allocations
• Simplifying logic
• Using optimized functions, e.g. cbrt(x) instead of x^0.33 (which leads to some small changes in the results)
• Renaming amount fields to more explanatory names
• Missing @test statements
• Using the same gravitational acceleration for sediment and local inertial flow (which leads to some small changes in the results)

Checklist

• Updated tests or added new tests
• Branch is up to date with master
• Tests & pre-commit hooks pass
• Updated documentation if needed
• Updated changelog.qmd if needed

[visr]

It will produce better code if this is marked as const. Not aware of plans to run Wflow on other planets, otherwise g_gravity::Float64 = 9.81 will also get most benefits.

[SouthEndMusic]

[visr]

Ah, I see you are turning into a proper earth scientist.