QA fix

dummy = true is needed for removed data
Predefine text formats left, right, centered
New option in sp: -c --config

This allows us to use a different config file than the default
"publisher.cfg" in the current directory.
sp: Use Go's routine for getting the homedir
Fallback when filename is missing on image

We should never throw a Lua error
Fix layout command sequence

We can now use <Sequence> to return any kind of data, not just elements with the
given name.
Bugfix for tables without output before

When we have a nested table without anything output yet on the page
we didn't have the "current grid".