Improves error message on systems that delve is failing on.

There were certain instances where the calculation of the stack frame
was incorrect, causing for garbage to be returned by a print command.

Currently there is no need for the other items in the ProcessStatus
struct, we really only care if the process is not running, so we can
avoid sending signals to it.

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

when evaluating a nil pointer.

* First of a few commits to allow for evaluating arrays of arbitrary
  types
* Adds support for 32 bit integer arrays