Currently only covers what is needed to keep code compiling, plus
everything caps/structure/tags related.
This avoids unnecessary heap allocations for adding the NUL-terminator
of C strings, and especially makes caps/structure handling as efficient
as in C.
Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer-rs/-/merge_requests/1190>
As a side-effect, this also now includes the element factory name in the
error messages instead of giving the same error string for every
factory.
Partially fixes https://gitlab.freedesktop.org/gstreamer/gstreamer-rs/-/issues/318
Also let them all go through the same, single object construction code.
The 'failure' crate has been stale for quite some time and better
alternatives has been developed since its introduction. We choose the
'anyhow' and 'derive_more' to replace it.
This code rework the examples to use the new 2018 edition and also
rework the code to avoid using unnecessary 'extern crate' calls.
The 'use extern crate gstreamer as gst', as well as the other gstramer
related crates, were kept, otherwise we'd need to do it on 'Cargo.toml'
but it would make it more difficult to figure out the respective crate
name.
... in function signatures.
These breaking changes aim at improving usability by allowing users
to take advantage of Rust error management features sur as `ok_or`,
`map_err`, `expect` and the `?` operator. See the `examples` and
`tutorials` to get an idea of the impacts.
