Scala mode indentation

Hi,

Scala mode uses the same indentation function that is used for other C-like languages. However, in Scala semicolons at the end of lines are optional, and the convention is to omit them. This causes issues when trying to work on Scala code in Qemacs, as new lines of code are incorrectly indented as if they are a single command split across multiple lines.

I've looked at c_indent_mode() in clang.c to try and special-case this, but it's not obvious how and where trailing semicolons are handled.