Fix `MULTILINES` regex to also match "\n\n"
Fix `MULTILINES` regex to also match "\n\n"

We want to catch errors on multiple lines, t.i. the string contains a
`\n` plus *any* other character (the `.`) including other newline chars
(`(?s)`).

Note: We don't just look for a single `\n` because linters might report
exactly on the EOL position.

SublimeLinter/SublimeLinter3,SublimeLinter/SublimeLinter3