Add support for decimal comma

[andstor]

Decimal numbers are currently supported. However, only support for decimal points . are implemented while decimal commas , aren't.

It should be possible to implement decimal commas. However, there are some caveats that needs to be resolved first. See issue #44. This is also related to issue #47 and #48.

When the issues above are resolved, it should be made optional whether to allow only decimal points or decimal commas as input (in floating numbers). As default it should be possible to use both types as input.

Since Maxima only allows decimal points in floating numbers, all transpiled floating numbers should only contain decimal points.