Performs Theil-Goldberger for theilbv model
results=theilbv(nlag,tight,weight,decay,arg1,...,argn)
* y = nobs x 1 input vector
* x = nobs x nvar input explanatory variables matrix
* nobs = # of observations
* neqs = # of equations
* eqn = # equation number
* nlag = the lag length of the VAR
* theta = Litterman's tightness hyperparameter
* weight = Litterman's weight (matrix or scalar)
* decay = Litterman's lag decay = lag^(-decay)
* scale = scaling vector (determined in bvar)
* scale2 = scaling vector (determined in bvar)
* nx = # of deterministic variables excluding constant term
* results = a results tlist with:
. results('meth') = 'bvar'
. results('beta') = bhat
. results('tstat') = t-statistics
. results('tprob') = t-probabilities
. results('yhat') = yhat
. results('resid') = residuals
. results('sige') = e'*e/(n-k)
. results('rsqr') = rsquared
. results('rbar') = rbar-squared
. results('nobs') = nobs
. results('nvar') = nvar
. results('xpxi) = inv(x'*x)