Refactor code for sorting scores into a helper function

[elray1]

The code in this block is making some decisions that seem to work but may not be optimal, and is not tested. Additionally, the sorting functionality may be useful more generally, so would be helpful to have it pulled into its own function.

predevals/src/predevals.js

Lines 505 to 521 in f268127

	// sort scores
	// TODO: refactor to a function for sorting scores, shared with plot code
	// use of d3.ascending() and d3.descending() is verbose,
	// but it works reliably for all data types
	// (have not thoroughly explored alternatives)
	const sort_models_by = this.state.sort_models_by;
	if (this.state.sort_models_direction > 0) {
	this.state.scores_table.sort((a, b) => {
	return d3.ascending(toLowerCaseIfString(a[sort_models_by]),
	toLowerCaseIfString(b[sort_models_by]));
	});
	} else {
	this.state.scores_table.sort((a, b) => {
	return d3.descending(toLowerCaseIfString(a[sort_models_by]),
	toLowerCaseIfString(b[sort_models_by]));
	});
	}

Other issues where sorting would be helpful: #3, #11