dc96475f58 Add/fix alloc features (Tobin C. Harding)
Pull request description:
Eventually we would like all our crates other than `bitcoin` to be able to be used without an allocator. Currently, and during crate smashing, this is not that useful because so much of the code comes from `bitcoin` and relies on the availability of an allocator.
As an initial step, add the `alloc` feature to `addresses` , `base58`, and `primitives`.
In order to to keep `--no-default-features` builds working make the crates empty if the `alloc` feature is not enabled. This is a suboptimal solution because the error messages users will get when they forget to enable `alloc` will be confusing (eg something like primitives does not contain Transaction). However our CI script (`run_task.sh`) expects `--no-default-features` to build cleanly (as do I).
ACKs for top commit:
apoelstra:
ACK dc96475f58
Kixunil:
ACK dc96475f58
Tree-SHA512: 28006ad638e72d3c712becaf94f6aaddc559fb2f7e7ad0d0810348fe979fb61e32f53e5b20894e472c5ac9e2b7f80cba6a3f0e12b766b817f412a927957ae3a2
6c8f759676