Because features and dependencies share the same namespace, and we want
to pass down the optional dependence on serde to bitcoin_hashes, we need
to rename the feature to something other than serde. Right now only
features can be passed down to dependencies.
Note that we could have also renamed the dependency to something like
serde-dep and kept the same feature name, however, dependency renaming
has only been available since cargo 0.27.0
Features that represent optional dependencies have been prefixed with
'use-'. The travis file has also been modified to conform to this
change.
The `serde_struct_impl!` macro has been modified to be compatible
with the serde 1.0 crate, we use this macro and not the `serde_derive`
crate because the latter doesn't support Rust 1.14.0 which is shipped
on Debian stable and we should remain compatible with it.
Two new features were added:
- "serde": enables serialization/deserialization for common types, it pulls
the serde 1.0 dependency.
- "serde-decimal": enables serialization/deserialization for `UDecimal`/`Decimal`,
this pulls the strason 0.4 depdendency and the serde 1.0 dependency.
Signed-off-by: Jean Pierre Dudey <jeandudey@hotmail.com>