When using a Special Type CDEF it should use only the SELECTED DEF type

[cigamit]

Describe the bug When you select a CDEF that does things like 'Total All Data Sources', it should only total the selected data sources of the selected DEF. Presently, the behavior is ambiguous and will use whatever it can, which should not be the intention.

To Reproduce Steps to reproduce the behavior:

1. Create a Manual Graph
2. Start adding Lines for Data Sources using 'AVERAGE' DEF
3. Add a AREA:STACK with the special Data Source type of 'Total All Data Sources', use MAX DEF
4. See that the AREA renders using the AVERAGE DEFS

5. Change one of the Line Data Sources to MAX DEF see that the total is now wrong, or rather different.

Expected behavior The Special Type Data Sources should operate only on DEF's that match the DEF of the Special Type Data Source.