Adds handling for more entities and also for numeric entities

[cgreening]

I was inspired by your unordered map solution and decided to add more entities along with handling for numeric entities.

I've pulled out the entity handling function so that it can be used anywhere - I wanted to make sure book titles would be properly parsed as well.

[martinberlin]

Very nice refactoring. I will test it tomorrow morning and also try to run this tests in my Ubuntu laptop with Platformio.