New attribute:
- `id: n` (on a table field): manually set the field identifier to `n`.
If you use this attribute, you must use it on ALL fields of this table,
and the numbers must be a contiguous range from 0 onwards.
Additionally, since a union type effectively adds two fields, its
id must be that of the second field (the first field is the type
field and not explicitly declared in the schema).
For example, if the last field before the union field had id 6,
the union field should have id 8, and the unions type field will
implicitly be 7.
IDs allow the fields to be placed in any order in the schema.
When a new field is added to the schema is must use the next available ID.
Change-Id: I8690f105f3a2d31fdcb75a4fab4130692b12c62f
Tested: on Windows
This is a breaking change, anyone having schema files with enums
that do not specify a type will get a specialized error:
must specify the underlying integer type for this
enum (e.g. ': short', which was the default).
All of the samples and docs already had a type specified,
so hopefully this will affect very few people.
Bug: 15777205
Change-Id: I9b8d7c0827867f7efb6c217346db7e402695eff0
Tested: on Windows
