#715 JS/HTML code generation: print model state

• Best to review per commit.
• Main change, for JS/HTML code generation:
  • Log initial state + state after event transitions.
  • For HTML: log panel shows horizontal scrollbar, doesn't wrap. Much easier to read then, in case of long 'state' logging lines.
• Some other related changes as well:
  • Fixed valueToStr for JavaScript Symbols. Symbols are only used for enumeration literals. valueToStr is used in multiple places, such as:
    • Error messages such as for index of bounds.
    • fmt arguments for for %s and %S.
    • String representation of tuple elements.
    • Output of print declarations.
    • State logging.
  • Improved comments in generated code, and text in generated reports, for location pointer variables:
    • Include location pointer variables in 'original declaration names' mapping.
  • JS/HTML code generation simplifications:
    • Simplified code generation of frequency slider code.
    • Simplified code generation of logging-related code.
    • A 'log' function is always present now, also for JS, not only HTML.
    • Prevents having to prefix all JS log calls with 'console.'.
    • Unchanged: JS/HTML log to console. Only HTML logs to the log panel.
    • Transition logging code is hard-coded in the template now.

Addresses #715