ring_partition: Ring partition for the block-LEnKPF
In robertsy/assimilr: Local Ensemble Kalman Particle Filters

Partition the observations in blocks for assimilation with block-LEnKPF. Takes into account the ring geometry. We assume that R is diagonal and don't take it into account

1	ring_partition(H, taper, block.size)

`H`	the observation operator
`taper`	the tapering matrix (qxq)
`block.size`	chunk size in domain space to take into account for one block

ndim <- 100
taper <- ring_GC(ndim, 5)
H <- diag(ndim)
partition <- ring_partition(H, taper, 5)
partition <- ring_partition( matrix( c(rep(0,ndim-1),1),1,ndim), taper, 5)
H <- matrix(0, 1, ndim)
H[1,round(ndim/2)] <- 1
partition <- ring_partition(H, taper, 5)