Bug 23900: Teach label maker to concat database fields

Bug 23900: Teach label maker to concat database fields

Test plan:
- define a label layout with this field list: "100a 245s","enumchron copynumber"
- find or create a record with values for all of those fields
- generate a label for that record
- the 100a and 245s successfully display on one line
- the enumchron and copynumber are displayed and separated by a space

Try other combinations

Signed-off-by: Andrew Fuerste-Henry <andrew@bywatersolutions.com>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Joy Nelson <joy@bywatersolutions.com>