* Add FLATBUFFERS_COMPATIBILITY string
- Add a new __reset method NET/JAVA which hides internal state
* Resolve PR notes
* Use operator new() to __init of Struct and Table
* Restrict visibility of C# Table/Struct to internal level
This is done on purpose, to avoid API version mismatches that
can cause bad decoding results, see:
https://github.com/google/flatbuffers/issues/5368
Change-Id: I2c857438377e080caad0e2d8bcc758c9b19bd6ec
vtable and vtable size depends only on `Table#bb_pos` but calculated in
`Table#_offset` method on each field lookup.
Doing this with every call of `Table#__offset` is redundant.
These values can be read once with change of `Table#bb_pos` and reused
for any field lookup.
