Set imEntity correctly in demo.html based on selection

[heralden]

@Sakshisrivastava413 suggested changing the demo.html imEntity dataToInitialiseToolWith based on the class you choose in the setup. This should definitely be done!

We can also do the same with the accepts (id or ids). Since you can select multiple classes or accepts in the setup, we should default to using the first of each for the demo.html. We also need to save some gene and protein IDs somewhere, and throw in one or more of them based on what the user selects during setup.