Support all types

[nalenz-objectbox]

Double-check that we at least support the basic Dart types for entity properties and as query conditions: int, double, String, bool.

If we don't support byte arrays yet, create a separate ticket; as far as I can tell there is Uint8List and potentially ByteData to be supported.

[Buggaboo]

This is holding me back in the Query dept. I'll see what I can do, after I'm done with the findIds, find, findFirst, remove etc.

[vaind]

Adding to the top of the to-dos for the next release as it is quite necessary for other tasks

[vaind]

Also, I've got info that dart int is currently stored as 32-bit - it should be 64-bit (i.e. core long & flatbuffers 64-bit int).

[greenrobot]

Welp

[vaind]

followup in #84 and #85