Fix some tr()-messages in the Debugger plugin.

Change-Id: Ie3145e90066432074fc44c77eeee027f57edfcf4
Reviewed-by: hjk <hjk121@nokiamail.com>
Use POSIX-compliant "." instead of "source"

Using "source" to source a script isn't defined by POSIX sh, while "."
is. Using the more portable "." makes it work with QNX's sh.

Change-Id: I948fc562c62789184553d57b949697c2525771f3
Reviewed-by: hjk <hjk121@nokiamail.com>
Reviewed-by: Christian Kandeler <christian.kandeler@digia.com>