Remove `$tutorGraduate` global variable in favor of `needsTutoring` function.  Improve display of schoolroom remaining lessons.

This reverts commit 91a71505.

Move all slave lists to pure DOM output, and use <<includeDOM>> to include them in their host passages.
Simplify NGP slave selection a bit and remove the $slavesToImport global.
Split JS portions of underperformingSlaves.tw into underperformingSlaves.js.

Add agent partner to diplomacy page too (because they're even *harder* to find than the agent).

This make them visible in the archaic untabbed UI and fixes the second
part of the #1810.

Change the job id array type to dictionary of string to set of number.
Use IDs in the listings and kill index-based functions in the facility
classes.