[ENHANCEMENT] Reflection caching

[EliteMasterEric]

Querying the list of properties and fields on an object on HXCPP platforms is very expensive, and it could be a moderate performance benefit to cache this information when able.

• Create a map and store the result of Reflect.fields() on scripted classes.
• Check whether a field is a property and use setField over setProperty where appropriate.
• Check timings to gauge performance improvements.
• Check whether reflection caching is slower than not using it on JS.