ENH: Improved ExecutionModelTour pointfile example

Fiducial node selector widget created for pointfile field does not support selection of multiple nodes
therefore adding a <pointfile multiple="true" ...> tag in the ExecutionModelTour example was misleading
(it will never get multiple files).
=> removed multiple="true"

Pointfile with channel="output" is a regular file field (same as transform, image, table, etc),
therefore adding a separate "File return types" section in the XML was misleading.
=> moved the field from separate section to right after the pointfile with channel="input", so now
it looks the same as all other file fields

git-svn-id: http://svn.slicer.org/Slicer4/trunk@24812 3bd1e089-480b-0410-8dfb-8563597acbee