Type cache for fast type_all(..) requests

[joente]

Description

This pull request introduces type cache. To be used, it must be set on to a type. If on, instances of a type will get their own lookup. As we might have circumstances where type_all(..) is used frequently on certain type, we benefit from a cache as otherwise we need to search between all things. The speed-up might be 10x faster or even more depending on the number of things in a collection.

(see discussion: #437)

Type of change

• New feature (non-breaking change which adds functionality)

How Has This Been Tested?

• Test type

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• New and existing unit tests pass locally with my changes