View source for ChucK/Dev/Shell/cmd

* shell commands 
** <code>vm attach [hostname[:port]]</code> or <code>vm @ [hostname[:port]]</code> attempts to attach to a ChucK VM running on hostname:port.  The default port is 8888.  If no hostname or port is specified, the shell attempts to attach to the in-process VM
*** prints a success message and the VM reference number for each successful attachment; prints a failure message for each failed attachment
** <code>vm + </code> or <code>vm add</code>
*** saves the current VM for later use
** <code>vm - [vm_reference]</code> or <code>vm remove [vm_reference]</code>
*** removes specified VM--it is no longer on the VM list
** <code>vm = [vm_reference]</code> or <code>vm swap [vm_reference]</code>
** <code>vms</code> or <code>vm list</code>
*** lists all VMs plus the current VM
** <code>vm @+ hostname:port</code> adds and attaches the specified VM
** <code>add [files]</code> or <code>+ [files]</code>
*** adds [files] to current VM and prints out a shred reference number for each file
** <code>remove [ids]</code> or <code>- [ids]</code>
** <code>removeall</code>
** <code>replace id filename [id filename]...</code>
** <code>--</code> (remove shred with highest id)
** <code>status</code> or <code>^</code>
** <code>kill</code> kills the current vm--shuts down the shell too if current_vm is the process vm
** <code>ls</code> (like unix ls)
** <code>alias</code> and <code>unalias</code> (simple substitution-based, bash-like command aliases)
** <code>shreds</code> list all shreds on the current VM
** <code>pwd</code> 
** <code>cd</code> (change directory, also change current dir for chuck so paths are consistent)
** <code>exit</code> exit everything
** <code>close</code> close down shell, keep process VM running
* Ge: thoughts on these commands? ^
** they look great!  few questions/thoughts:
*** depending on the command line flag issued, the shell could automatically attach the most appropriate thing
*** (maybe by default, the shell is attached to 'process'
*** --local and --process probably don't need to be be flags since they are targets of the attach shell command  (local or process or self may suffice?)
*** the multiple attached target vms is totally cool!