Convert Tortoise to use ES6 modules

[LaCuneta]

Galapagos was converted to use ES6 modules along with Rollup to create minimized code for each page-specific bundle. That has worked well for that project. It would be nice if Tortoise was converted as well, to make it easier to include dependencies that are already updated to ES6 modules. Some considerations for the switchover:

• Generating a minimized version as well as a maximized version with full variable names and whitespace.
• Enabling the dynamic import of extensions as modules instead of their current state as statically included in the engine.
• Possibly swapping the final published artifacts from webjars to a standard npmjs package.