pty 0.2.2

Fork with new pseudo-terminal (PTY)
Documentation
### 0.2.0
* Improve the Error Handling.
* Improve the POO representation.
* Remove the **posix_openpt**(3) call.

### 0.1.6

* [#5]https://github.com/hibariya/pty-rs/pull/5 Improve error representation

### 0.1.5

* API Change: [#3 Remove unnecessary `Copy` trait]https://github.com/hibariya/pty-rs/pull/3
  * Mark `Child#pty` as private, add public `Child#pty()`.
  * Remove `Copy` trait from `Child` and `ChildPTY`.
  * Remove `ChildPTY#fd()`, impl `AsRawFd` for `ChildPTY`.
* Bug fix: [#4 Continue wait if it's still alive]https://github.com/hibariya/pty-rs/pull/4

### 0.1.4

* API Change: [#2]https://github.com/hibariya/pty-rs/pull/2 Make `pty::fork()` return a single value.

### 0.1.3

* Support stable rust