* `TlsProfile` is better off sticking to the style used in standards.
* `bearssl-sys` bindings can't be annotated with safety as they are
autogenerated and have the same safety properties with the library
* I believe working around `br_sslio_*` isn't worth the effort as the
same functionality can be done manually with `*_buf` + `*_ack` which
is used by sslio internally. This will especially be useful when
wrapping Write/Read traits in std.
* Since both server and client contextes use `br_ssl_engine_context`,
writing the routines for it removes a lot of future headaches. The
engines shouldn't be used directly but will be exposed anyway for
special cases and for having more discoverable errors.
* Reduce the version of `bearssl` to 0.0.2 to increment minimally from
the existing crate.
* Add an overview README for a high level description.
* Add crate tags and categories for easier discoverability in the