Link to mixed in pseudo-types

Also rename `number` to `num`.
Mentioned in #170
Remove "definition is not used at run time"

Closes #399
toImmVector returns an ImmVector, not a Vector

Closes #402
Document __ConsistentConstruct

Fixes #380
Remove two notes and make UNSAFE_Construct more clear
Don't use Parent in examples
Generic-style constraints are not supported in opaque types
ConsistentConstruct Grammar Fix
Forgot semi-colon in opaque type alias warning
Document ReflectionClass::getStaticPropertyValue optional param

Closes #409
Pairs are readonly and fixed