update_invW: Update M = inv(W)
In acabassi/variational-ogc: Variational Outcome-Guided Clustering

Update M = inv(W)

1	update_invW(X, Resp_k, M0_k, beta0_k, m0_k, xbar_k, indep)

`X`	NxD data matrix.
`Resp_k`	Vector of responsibilities for mixture component k.
`M0_k`	Prior precision for mixture component k.
`beta0_k`	Prior beta for mixture component k.
`m0_k`	Prior m for mixture component k.
`xbar_k`	Weighted mean for mixture component k.
`indep`	Independent covariates (boolean).