[parrot/parrot] d8ae34: [pmc] add missing StringHandle methods

[GitHub]

  Branch: refs/heads/smoke-me/sh-peek-gh1011
  Home:   https://github.com/parrot/parrot
  Commit: d8ae34f04c0608879a53b087fdecee6a60b52f2b
      https://github.com/parrot/parrot/commit/d8ae34f04c0608879a53b087fdecee6a60b52f2b
  Author: Reini Urban <rurban at cpanel.net>
  Date:   2016-02-16 (Tue, 16 Feb 2016)

  Changed paths:
    M src/io/stringhandle.c
    M src/pmc/stringhandle.pmc
    M t/pmc/stringhandle.t

  Log Message:
  -----------
  [pmc] add missing StringHandle methods

Similar to the FileHandle PMC: tell, seek, peek.
Add more error handling to StringHandle->seek (out of bounds)
Add testcase t/pmc/stringhandle_26

Fixes GH #1011