Save the useMathView user setting on the User Settings page

[xcompass]

Summary

When $pg{specialPGEnvironmentVars}{entryAssist} is set to 'MathView', the User Settings page (templates/ContentGenerator/Options.html.ep) shows a "Use Equation Editor?" radio group named useMathView. However, WeBWorK::ContentGenerator::Options::initialize never reads that parameter when saving display settings — the change-detection condition only checks displayMode, showOldAnswers, and useMathQuill, and the save block only writes those three fields. As a result the submitted useMathView value is silently discarded and the setting reverts to the course default ($pg{options}{useMathView}) on every page load.

This adds useMathView to the change-detection condition and saves it on the effective user record alongside the other display settings, exactly matching the existing handling of displayMode, showOldAnswers, and useMathQuill.

Testing

• With entryAssist => 'MathView' set in specialPGEnvironmentVars for a course, toggle "Use Equation Editor?" on the User Settings page and save: the user.useMathView field is updated and the selection persists after a reload (previously it always fell back to the course default).
• The MathQuill flow (entryAssist => 'MathQuill') is unaffected: the added disjunct is guarded by defined($c->param('useMathView')) and is inert when the MathView radios are not rendered, and useMathView($c->param('useMathView')) then stores undef/NULL exactly as the existing code already does for the unrendered useMathQuill parameter in the MathView flow.
• perltidy (Perl::Tidy 20260204, as pinned in .github/workflows/check-formats.yml) produces no changes on the modified file.

[drgrice1]

The fact that none of us notices this shows how little MathView is used anymore. In fact, we will most likely be removing it soon. Unfortunately, it is vastly inferior to MathQuill. Also, I have been maintaining MathView, but that takes a lot of effort for this archaic approach to entry assistance.

[xcompass]

Totally understand. Just happen to notice this when we are doing merge to our fork.