Errors List Corrections

While testing the error highlighting, some problems were found.  The first one exhibited itself as the last error was not correctly updated when it changed.  The problem was that a new error was being incorrectly inserted each time an error was changed.  This occurred in the set error routine in the program model because it did not return after replacing an error and it proceeded to also insert an error.

The set error routine was cleaned up where the first part now specifically handles changes (not inserts) and returns after an error is removed (the line no longer has an error), or an error is replaced (the line still has an error).  The rest of the routine handles inserting a new error and adjusting the rest of the error indexes and line numbers (for line inserts).  The remove error routine contained an else clause for exiting when called for an insert, but since this no longer occurs, the else clause was removed.

The second problem was in the edit box update errors slot.  The problem occurred when two or more lines with an error were removed and all the errors were changed as a result (due to the line numbers changing).  The problem is that the ending change index is set to the last index upon the first removed error, but after the second error is removed, the ending change index is not beyond the end of the error list.  This caused the routine to run past the end of the errors list causing a segmentation fault.  This was corrected by limiting the number of errors changed to one less than the size of the errors list.

[commit 30e7d98a1d] [commit 65893e51f9]