[perl #31731] [TODO] Tcl parser, return codes

# New Ticket Created by  Will Coleda 
# Please include the string:  [perl #31731]
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# <URL: http://rt.perl.org:80/rt3/Ticket/Display.html?id=31731 >


The parser should, like the interpreter, return a status that indicates whether 
or not the code snippet parsed cleanly. (TCL_OK vs. TCL_ERROR) 

Then, we can throw the appropriate errors during the parse process (As opposed 
to now, where we print and abort.).

This is going to mean that any call to _Tcl::__parse needs to have its return 
type checked.

For now, returning the error as a string-y PMC (in place of the array of tcl 
words) will be fine.