Code formatter fails when an underscore is used in a big number

[bulent2k2]

Here is a sample:

clearOutput
val big= 200_000_000
println(big / 100_000.0)

This code compiles and runs. However, when we run "Format Source" command, we get an error:
Unable to format: Invalid literal number: _
and the formatter fails to format the code.

[litan]

We depend on Scalariform for this, which does not explicitly support Scala 2.13 (where the use of underscores in numeric literals was introduced).