Fix for hang during painting

We had an odd problem where opening an alert dialog right after adding
an element would cause hangs in the app. This was a result of the
element not having been placed yet, and the painter for it crashing in a
spot that SWT wasn't good about reporting the error back.

This commit now provides a check for the object to make sure that it's
positioned, and also has a rescue clause to keep errors from escaping.
Force positioning before allowing dialogs

This allows the common painters to get the positioning they need before
SWT's open triggers paint events on unpositioned elements.
Fix for flipped logic on positioned? in painter

Also consolidated to use just absolute_left/top and added a spec.
Fix spec failure for line

Changes in requirements for painter to run weren't set properly in this spec.
Some specs for the painter and the positioned functionality
Merge branch 'master' into painter_alert_fail
Log an error message for swallowed errors + fix shape

* definitely logging and maybe something better otherwise way too
  many errors may escape us.. or evaluate if we really need that
  swallow everything rescure clause
* keeping shape up with dimensions... really need to get it
  dimensionized :(
expert-definr is not working anymore see #663