Granger (non-)causality tests for a rolling VAR
res=rolvar_granger(res_rolvar,causing,caused,noprint)
res_rolvar = a 'rolling var' results tlist
option = the result the user wants to plot ('chi2 stat', 'chi2 pvalue', 'Fisher stat' or 'Fisher pvalue')
rvar = a results tlist with:
* rvar('meth') = 'rolling var Granger causality'
* rvar('rolvar res') = the input 'rolling var' results tlist
* rvar('causing') = the index vector of the supposed causing variables
* rvar('caused') = the index vector of the supposed caused variables
* rvar('chi2 stat') = the vector of rolling Wald statistics of non-causlity
* rvar('chi2 pvalue') = their p-values
* rvar('Fisher stat') = the vector of rolling statistics of non-causlity inf Fisher form
* rvar('Fisher pvalue') = their p-values