Fix handling of uint64 on old version of Nim

Fix accepting Option params

Fix leak of Reference-inherited objects

Bump version to 0.8.2

Fix wrapping methods with Array return types

Break reference cycle in NimGodotObject

More efficient and GC-safe conversions in API generator

Up version to 0.7.27

Fix unsigned int conversion to/from Variant

Do not log error when casting fails

This allows not to perform unnecessary 'of' check before
casting, if cast failure is expected.