Add tests for the setoptions package and fix code

[dpvc]

This PR adds tests for the setoptions package, and updates its configuration file.

The changes to the configuration include:

• Breaking the error message at 82-86 into two messages, one for the TeX options, and one for package options, mirroring the messages in (original) lines 91-103.
• To do that, the isTexvariable is moved earlier to line 78.
• The filterValue() function is extended to handle RegExp values (like the one for the ams parameter operatornamePattern).
• The setoptions command map is now created within the setoptionsConfig() function. This means that the map will be recreated for each instance of the setoptions package, so if there are two TeX input jax created, one with [tex]/require includes and one without it, the first will get the updated \require macro that allows options, while the second will have the original \require. The original version would have shared the setoptions map between the two, so both would get the updated \require.

[zorkow]

lgtm.