#227 CIF code generator for HTML now supports SVG input mappings with updates + related improvements/fixes

• Easiest to understand per commit. I tried to introduce the changes in a logical order. There may be some small things that get changed again in a later commit, but I'm not sure.
• End-user visible changes:
  • CIF code generator for HTML now supports SVG input mappings with updates.
  • CIF code generator for HTML now initializes input variables to their default values.
  • CIF code generator for HTML now includes input variables and their values when printing states to the log panel.
  • CIF code generator for HTML now properly executes SVG input events before uncontrollable events.
  • CIF code generator for HTML now processes all SVG image interactive element clicks in a single execution of the corresponding event loop, even if certain SVG input events are not enabled, thus ensuring that all clicks have been processed before executing the uncontrollable events event loop.
  • CIF code generator documentation has some textual improvements.
• Other changes:
  • CIF code generator: mostly changes for assigning input variables, adding environment events, and supporting updates of SVG input mappings.
  • CIF code generator: several internal code/comment/JavaDoc improvements.
• I noticed that if SVG input mappings with events are incomplete, no error is generated. I've made issue #1069 (closed) for that. I'll solve that after this one.

Addresses #227 (closed)