removeJob() can select new assignment for a slave, so we have to remove
it from that one, instead of the assignment the slave came to assignJob()
with, when moving him to a new assignment.

Hopefully fixes #1808.

VSCode completion inserts them sometimes (don't know what triggers
that), but inside the SugarCube 'this' is different, apparently.

Fixes #1811.

Fixes #1810.

removeJob() does not only clean the assignment, but also sets a new one
(e.g. "rest"), so we have to remove the slave from that set.

Fixes #1808.

Fixes #1805.

Probably fixes #1804.

Put economics and workers firing into helper functions

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.

The classes are used only to set up data scheme, thus they need no JS
implementation.