use one call to add-text... to add text
add double digit values in text
do first vis-loc search for right-most text
added fields to imaginal buffer type
attend and encode ones place of second number
renamed encode production
changed state name in goal after encode second ones
added comments
indentation
added production for finding plus
search for rightmost text left of plus
fixed new goal state after finding first ones
attend ones place of first addend
encode ones place of second addend
added ones and carry slots to arithmetic dms
added ones and carry slot to arithmetic chunk type def
production to start adding ones places
updated production for requesting addition dm retrieval
added ones carry and tens slots to goal
updated retrieve results production
added slots for storing x loc of plus sign and ones place of second addend