fix double.roundToPrecision

[UliPlabst]

This fixes #34. The issue turned out to be not the rounding itself but the calling of detectPrecision in a wrong way. Let's look at the implementation of detectPrecision:

powerbi-visuals-utils-typeutils/src/double.ts

Lines 472 to 487 in c6485ad

	export function detectPrecision(precision: number, x: number, y?: number): number {
	if (precision !== undefined) {
	return precision;
	}
	let calculatedPrecision;
	if (!y) {
	calculatedPrecision = getPrecision(x);
	}
	else if (!x) {
	calculatedPrecision = getPrecision(y);
	}
	else {
	calculatedPrecision = getPrecision(Math.min(Math.abs(x), Math.abs(y)));
	}
	return calculatedPrecision || DEFAULT_PRECISION;
	}

As I understand if it get's passed a precision that is not null it just returns it. If precision is null then it detects the precision based on the boundary values x and y. If the precision is null it returns DEFAULT_PRECISION.
So the call

powerbi-visuals-utils-typeutils/src/double.ts

Line 356 in c6485ad

precision = detectPrecision(precision, DEFAULT_PRECISION);

in double.roundToPrecision does not make sense. As I understand it should pass x instead of DEFAULT_PRECISION.
I also added some more test cases to verify my problems were fixed. All tests pass for me.

[helen508light]

Have added task with this PR to our typeutils tasks backlog. It would be reviewed soon

[helen508light]

Also @UliPlabst please update your changes, now they are out-of-date

[UliPlabst]

@helen508light I updated the branch. Can you merge it?

[helen508light]

@UliPlabst
I've created task for this changes and it will be reviewed by team, but there is not ETA

[UliPlabst]

okay thanks.