Diagnostics: fixed trac=OK (refs #398)

Fixed bug introduced in [992641b46f3578c16c56c7523ada55f10eaeac17]:
Somehow I missed checking the code before commiting, there was a
piece of prototype code/data left.
Code cleanup, removed futurewarning
Added intial submin2-admin diagnostics command (refs #393)

The html template is converted to a commandline output template. The output
is working, but there are still some formatting problems (especially unwanted
newlines and incorrect indenting).
Allow newlines to be used as separators

There is usually no need to insert extra newlines between the template command
and its arguments. If you do need a newline, use a space or newline and then
a newline to insert a newline.
Template: Added suppress_newline modifier

If a command is prefixed with '@', the newline directly following the
command node is suppressed. This means that the command should be followed
by a textnode that starts with a '\n' character for it to have any effect.

The reason for this feature is to allow for newlines in the template for
readability of the template, but no newlines in the output (also for
readability). This is not that necessary for HTML templates, but it is for
plain text templates.
Nicer formatting of diagnostics CLI (refs #393)

Using the new 'suppress newline' modifier of the templates, we increase both
the readability of the template as well as the output. The newlines are
suppressed on all 'test' and 'else' commands, even though it might not be
necessary for all of them. In any case it's better to be consistent.