its alright. i just got a bit emotional as i spent a lot of time on this
refactoring this week :-)
in the sql parser, i simply chose the nodetypename as selector name if
there is no explicit name, and when rendering that to sql2 i check if
the selectorName happens to be the type name and in that case omit it.

indeed we should dig up the jcr definition for a valid selector name. if
it can't contain ":" then i really don't know what to do. we could make
our qom factory have an optional parameter for the sql parser to say
that here its ok to not have a selector name, so we can still use the
qom factory for the parser. but that feels rather ugh.