API to generate .rs files

This API does not require protoc command present in $PATH.

```rust extern crate protoc_rust;

fn main() { protobufcodegenpure::Codegen::new() .out_dir("src/protos") .inputs(&["protos/a.proto", "protos/b.proto"]) .include("protos") .run() .expect("Codegen failed."); } ```

And in Cargo.toml:

toml [build-dependencies] protobuf-codegen-pure = "2"

It is advisable that protobuf-codegen-pure build-dependecy version be the same as protobuf dependency.

The alternative is to use protoc-rust crate which uses protoc command for parsing (so it uses the same parser Google is using in their protobuf implementations).

Version 2

This is documentation for version 2 of the crate.

In version 3, this API is moved to protobuf-codegen crate.