This commit makes the following changes: It defines the public
`otInstance` as an empty opaque structure which is used by all public
C OpenThread APIs. It defines a new class `ot::Instance` (inheriting
from `otInstance) which is then used in core source files. The
functionality related to the instance is also moved/added into the
newly added `Instance` class (as class/static or member methods).
This commit adds support for encoding/decoding `uint64_t`/`int64_t`
to spinel as primitive types. `X` and `x` are used as format ASCII
character associated with `uint64_t` and `int64_t` respectively.
This commit also updates the `SpinelEncoder` and `SpinelDecoder`
to add methods related to 64-bit long integer. The related unit test
are also updated.
This commit adds a new class `SpinelDecoder` which provides a set of
methods/APIs to help in decoding/reading content using Spinel formating
(it is practically a C++ wrapper over Spinel C APIs). A unit test
`test_spinel_decoder` is also added in this commit.
This commit also updates the `NcpBase` implementation to adopt the new
`SpinelDecoder` class mainly in set, insert, and remove handlers
for different Spinel properties. The new class provides similar advantage
as `SpinelEncoder` by simplifying the handler implementations and adding
type-check safety when parsing/reading the spinel frame.
Jonathan Hui