* Set hardware breakpoints on all existing threads
* Set hardware breakpoints on any new thread the spawns

Fixes #111

* Remove half baked CallFn implementation.
* Cleanup whitespace
* Cleanup read/write mem functions

Process is an incorrect name for the DebuggedProcess struct that the
thread is "a part" of. Also, no need to export that field.

* Properly find next source line for goroutines blocked in chanrecv
* Refactor breakpoint clearing
* Refactor temp breakpoint setting

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

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

As of go version 1.4 the standard library syscall package is "locked
down" and code outside of the standard library is recommended to migrate
to the go.sys subrepository.

Reference: https://golang.org/s/go1.4-syscall

Currently only works for amd64 processors.

Handle SIGINT by stopping the traced program and then displaying a
prompt to the user for commands. If the traced process is not running,
this is a noop.

Closes #30