String/Label routine operations

The following routine operations work as follows

Append To Label appends a formatted value/label to a label
Crop/Trim Label extracts a substring of a label name
Remove Label Extention assumes label is a filespec with an extention, removes the last "."
and everything following

If the resulting string already exists in the label list, the target
is now set to the index of the existing label, rather than a duplicate
label being created in the label list.

All models using these operations will need to be updated to check
if the target value has changed and use the new value. In addition the
modeller may want to delete the old label (before the operation) since
it will still be in the label list when an index to an existing label
(after the operation) is returned.

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idkbase note 2