Various updates

[JAL9302]

Adds a confirm box before deletions, and allows additionalProperties to correctly show up when the starting data is passed into renderObject has additionalProperties, and the schema contains additionalProperties.

Also adds a new helloworld html file demonstrating the new changes, specifically onde working with starting data containing additionalProperties.

[JAL9302]

@exavolt you still supporting this project?

[exavolt]

@jodoglevy Ah. Yes. Sorry for the late response. Got occupied by other projects.

I'll review the request tomorrow.

[JAL9302]

@exavolt I think the pull request you merged from @adamgreig fixes the additionalProperties issue I was trying to fix in this pull request. So you may not need that anymore (although I did not test to see if his code works for my helloworld test file included in the commits). But confirm on delete would still be useful considering hitting 'enter' when focused in an array currently deletes the current index that has focus (which I'm not sure is what it is meant to do), without prompt.