Scalariform should not fail on '_' in numeric literals

[diversit]

We change to use SonarScala plugin in SonarQube to scan our Scala code.
However, the scan fails on numeric literals like 100_000L.

This is caused by the function checkNoLetter in ScalaOnlyLexer L509.

Could the checkNoLetter function be changed to not fail on _ characters in a number since this is valid Scala code?

Error

scalariform.lexer.ScalaLexerException: Invalid literal number: _

Expected
Scalariform should not fail on literal numbers with _ like 150_100L.