API to generate .rs files

API to generate .rs files to be used e. g. from build.rs.

Example code:

``` extern crate protoc_rust;

protocrust::run(protocrust::Args { out_dir: "src/protos", input: &["protos/a.proto", "protos/b.proto"], includes: &["protos"], customize: Customize { ..Default::default() }, }).expect("protoc"); ```

And in Cargo.toml:

[build-dependencies] protoc-rust = "1.5"

Note this API requires protoc command present in $PATH. Although protoc-gen-rust command is not needed.

The alternative is to use pure-rust .proto parser and code generator.