* DebuggedProcess method: `PrintGoroutinesInfo` -> `GoroutinesInfo`
* `goroutines` command in command/command.go now responsible for
  printing info.

Add a couple of troubleshooting instructions for OSX users.

* Better tracking of current goroutine
* More efficient, eliminates superfluous step syscalls
* Handles concurrency and thread coordination better

This allows greater flexibility for using a port set and determining
whether the wait returned due to a breakpoint or process natural death.

Added Term object (terminal or terminator) that wraps the liner.State object so that it can be closed properly on exit. Changed a few functions (die, promptForInput, etc.) to be methods for Term.

Also refactored code a bit, removed printing functions from proctl
package and inlined them into command.

Allows compiling a test binary and debugging it.

Also, rearrange and cleanup file a bit.

Fixes #72