Does not support E notation for very small or very large numbers

While using this tool to get some kafka metrics into nagios we stumbled upon this error:

`Block [3.487953628987248E-5] in expression [3.487953628987248E-5 * 1] invalid`

It seems that this tool does not support numbers that use the E notation, like `1.2E-3`, into an `<expr>` element.
