Allow sub controllers to have a different label to their path name

[GDYendell]

• Depends on Allow numbers to be group names epics-containers/pvi#141

[GDYendell]

This might not be possible because qsrv / pvaccess does not allow fields starting with a number, so the PVI info creation fails:

ODIN:FP:PVI: Error Group not created: invalid field name "0"
ODIN:FR:PVI: Error Group not created: invalid field name "0"

[evalott100]

111287a seems to work, I'll make it better when I've decided what I'm doing.

FASTCS_PANDA:TTLIN1:PVI_PV
FASTCS_PANDA:TTLIN1:Term
FASTCS_PANDA:TTLIN1:Term_RBV
FASTCS_PANDA:TTLIN2:PVI_PV
FASTCS_PANDA:TTLIN2:Term
FASTCS_PANDA:TTLIN2:Term_RBV
FASTCS_PANDA:TTLIN3:PVI_PV
FASTCS_PANDA:TTLIN3:Term
FASTCS_PANDA:TTLIN3:Term_RBV
FASTCS_PANDA:TTLIN4:PVI_PV
FASTCS_PANDA:TTLIN4:Term
FASTCS_PANDA:TTLIN4:Term_RBV
FASTCS_PANDA:TTLIN5:PVI_PV
FASTCS_PANDA:TTLIN5:Term
FASTCS_PANDA:TTLIN5:Term_RBV
FASTCS_PANDA:TTLIN6:PVI_PV
FASTCS_PANDA:TTLIN6:Term
FASTCS_PANDA:TTLIN6:Term_RBV