Fix plex self reference debugbreak()

Now it produces a usable exception when the user causes a self
reference, which is just the full qualified name of something in the
same catalog file,
json parsing of objects

with minimal tests.
fix an generator issue in plex (raw strings)

Raw strings can have embedded linefeeds which cause the plex generator
to double the number of linefeeds .

This is a not-so-great fix for it but it does the trick.
fix generator issue part 2

fine tunning, see previous commit

Now the fix is even uglier.
more json object tests