Demo IOCs

ioccircle and ioccircle together demonstrate PVA groups and links.
ioccircle maintains a "phase" counter which counts from 0 to 359
then rolls over.

From this phase are calculated an X and Y which are points on a circule with radius 1.

A group PVA PV is defined which includes both and X and Y.

ioccircle2 contains two calc records which subscribe to the X and Y
from ioccircle and multiply each by 2.

A second group PVA PV is defined including the multipled X and Y.

Due to the atomicity of a group PV it is certain that pairs of
X and Y will not be mixed.  In this example, the magnitude
sqrt(X*X+Y*Y) will never change by more than floating point epsilon.
