{----

Concurrent loops at a signal buffer

Create a set of concurrent loops at a signal buffer.  This is the
static and composed variant of RFreezer.  There are five global
inputs, the buffer and then: left, right, gain and increment.  The
first two are initialization rate, the second two control rate.
Each loop is defined by a quadruple: left, right, gain and
increment.  The left and right values are in the range [0,1) and
refer to the segment of the buffer established by the group left
and right values, which are in the range [0,1) in relation to the
signal buffer.

Buffer Left                                  Buffer Right
|                                                       |
|      Group Left              Group Right              |
|      |                                 |              |
|------|----|-----------------------|----|--------------|
            |                       |
            Loop Left      Loop Right

-}