minor bugs

[PMildenb]

• fix return for wlsPower( ... , power=target, verbose=0)
• fix plot.DesMat when INDIV_LVL=TRUE
• INDIV_LVL and N varying over clusters
• INDIV_LVL and N varying over time (!)
• tau=NULL should throw only a warning (and not an error)
• add checks for maximum of incomplete
• make xgap and ygap dynamic (in plot_ly)
• combine alpha_0_1_2 and AR
• avg info content
• info content for entire clusters (closed)
• rename "wls" -> "gls" ?