Massive name changes to factory.

The changes make it clear what is a default implementation and
what implements base classes defined in pvData.h.

test/testPVStructureArrayDiff

@@ -1,57 +0,0 @@
-56a57,112
->  reference counts powerSupply referenceCount 1
->     value referenceCount 1
->     alarm referenceCount 14
->         severity referenceCount 14
->         message referenceCount 14
->     timeStamp referenceCount 2
->         secondsPastEpoch referenceCount 2
->         nanoSeconds referenceCount 2
-> before incReferenceCount reference counts powerSupply referenceCount 4
->     voltage referenceCount 4
->         value referenceCount 4
->         alarm referenceCount 14
->             severity referenceCount 14
->             message referenceCount 14
->     power referenceCount 4
->         value referenceCount 4
->         alarm referenceCount 14
->             severity referenceCount 14
->             message referenceCount 14
->     current referenceCount 4
->         value referenceCount 4
->         alarm referenceCount 14
->             severity referenceCount 14
->             message referenceCount 14
-> after incReferenceCount reference counts powerSupply referenceCount 5
->     voltage referenceCount 5
->         value referenceCount 5
->         alarm referenceCount 17
->             severity referenceCount 17
->             message referenceCount 17
->     power referenceCount 5
->         value referenceCount 5
->         alarm referenceCount 17
->             severity referenceCount 17
->             message referenceCount 17
->     current referenceCount 5
->         value referenceCount 5
->         alarm referenceCount 17
->             severity referenceCount 17
->             message referenceCount 17
-> after decReferenceCount reference counts powerSupply referenceCount 4
->     voltage referenceCount 4
->         value referenceCount 4
->         alarm referenceCount 14
->             severity referenceCount 14
->             message referenceCount 14
->     power referenceCount 4
->         value referenceCount 4
->         alarm referenceCount 14
->             severity referenceCount 14
->             message referenceCount 14
->     current referenceCount 4
->         value referenceCount 4
->         alarm referenceCount 14
->             severity referenceCount 14
->             message referenceCount 14