Use a more accurate number library

[zepumph]

From #113 and many other times since moving to javascript, there are rounding problems with javascript's floating point implementation.

We have reached the point that it would be nice to investigate another library, and we feel like it is potentially possible to do so in specific cases, instead of needing to use this everywhere all at once.

Marking as an epic.

[zepumph]

Some ideas about this over in #113 is to replace the ScientificNotationNode's usage of toExponential, and potentially to rewrite DOT/Utils.toFixed.

[kathy-phet]

Found a different solution. Closing, and will re-open if needed.