#715 HTML code generation: various improvements, mostly related to option/settings (!1507) · Merge requests · Eclipse Projects / Eclipse ESCET (Supervisory Control Engineering Toolkit) / escet

As preparation for adding speed settings to the generated HTML pages, I've factored out the following changes.
End-user visible changes:
- Some fixes in error messages of the 'HTML frequencies' option.
- Improved positioning and layouting of the 'settings' menu of generated HTML pages.
- Move frequency and 'show SVG image' configuration into settings menu, as we're getting to many settings with more being added later.
- The HTML code generation documentation section on settings has improved styling.
Other changes:
- Easier layouting of items in the 'settings' menu, when new menu items are added of different types (not checkboxes).
- JavaScriptCodeGen: renamed a local variable in generated code: range -> freqRange, to allow for more range element local variables to be added in the future.
- JavaScriptCodeGen: generalized a comment.

Addresses #715

#715 HTML code generation: various improvements, mostly related to option/settings