* Download sprout parameters in-memory
* Add download_sapling_parameters and deprecate download_parameters
* This avoids confusion between sprout and sapling downloads,
while maintaining backward compatibility.
* Download a single file, rather than parts
* This is more efficient, because TCP adjusts its transfer speed
in the first ~20 seconds of each new connection.
* Only download files if needed, but always check the hashes
* Allow the caller to specify a response timeout
* Stream downloads from server to disk
* Refactor file loads to use the same verifying function as downloads
* Check file sizes to help debug parameter load failures
* Remove downloaded files on error (but leave existing files alone)
* Add a sprout and sapling download example
* Move the download Read impl into its own module
* Derive standard traits on SaplingParameterPaths
* Require features for the load parameters method
Instead of imposing the requirement that bellman users explicitly
specify an engine for every proving system, we allow the Rust type
system to figure it out for us. An engine is specifically useful in
places where we require defined relationships between several types;
ff::ScalarEngine only has one type, and thus any usage of it can be
trivially replaced by an explicit Scalar type. This is also more
readable :)
teor
Jack Grigg
Eirik Ogilvie-Wigley