Use REST API instead of websockets to calculate additional variables

src/lib/calculations.ts

src/lib/components/WaterfallCompareView.svelte

src/lib/components/WaterfallView.svelte

src/lib/components/test_cases/TestCaseCompareView.svelte

src/lib/components/test_cases/TestCaseView.svelte

src/lib/components/variables/FormulaView.svelte

src/lib/components/variables/VariableInput.svelte

src/lib/situations.ts

src/routes/+layout.svelte