Clicking on error messages is supposed to jump to the editor.
And "Show Output" on the task is supposed to select the error
in the output.

The old code just registered the task for the last line of
output. This broke for every parser that allowed for
error messages that spanned multiple lines. And was obviously
also incorrect for tasks that weren't generated due to
compile output.

Fix both of those issues by giving the IOutputParsers more
control on which lines are linked to a task.

Task-number: QTCREATORBUG-14136
Change-Id: I095922c9875620dabfb7d406f6b152c8a9b25b62
Reviewed-by: Tobias Hunger <tobias.hunger@theqtcompany.com>
Reviewed-by: Daniel Teske <daniel.teske@theqtcompany.com>