connect program model error changes to edit box

added start/end indexes of changes to error list with access functions
overloaded functions in error list to capture start and indexes
modified program model to check when error list changes from an update
emit new signal from program model to send error list when changed
added new slot to edit box to update errors when changed (just prints)
connected new program model signal to new edit box slot in main window
changed rpn list to hold error column/length instead of token

there was no reason for the RPN list to have the error token
changed ErrorItem constructor to take rpn list instead of token/message
removed unnecessary blank line after error in test code
also fixed expected results files to remove unnecessary blank lines