Add support for blob type in sqlite3... it's unusual in that it
is created into the table schema as a column of blob type, but is
not serialized or deserialized into or from JSON or sqlite.
Because the size of blobs is open-ended, accessing them in one
hit may not be possible, eg, exceed the size of available heap.
As binary, they would have to be base64-encoded in JSON
representation and that bloating may be excessive, with, eg,
a 500MB blob. So while they can be defined using lws_struct
schema, and coexist inside a column of a table managed by
lws_struct, they must be read and written separately.
Continue with lws_struct, add sqlite support for one
level of lws_dll2_t lists of structs serialization and
deserialization, plus the matching api-test.
