Bring back online the creation of the window manager data model. This snapshot is currently broken at the window splitter level (not suprising given churn in the kohelpers-common.coffee file over the past day or two while this subroutine has been offline. This commit zealously instruments the top-level routine that builds the window manager's internal data model with try/catch blocks to make it simpler for me to systematically wring out the bugs and later to make it simple to diagnose problems with the input layout declaration.