metadata: Compact integer encoding.

Previously every auto-serialized tags are strongly typed. However
this is not strictly required, and instead it can be exploited
to provide the optimal encoding for smaller integers. This commit
repurposes `EsI8`/`EsU8` through `EsI64`/`EsU64` tags to represent
*any* integers with given ranges: It is now possible to encode
`42u64` as two bytes `EsU8 0x2a`, for example.

There are some limitations:

* It does not apply to non-auto-serialized tags for obvious reasons.
  Fortunately, we have already eliminated the biggest source of
  such tag in favor of auto-serialized tags: `tag_table_id`.
* Bigger tags cannot be used to represent smaller types.
* Signed tags and unsigned tags do not mix.

0 files changed, 0 insertions, 0 deletions