recovers objects names in an equation
[namey,ncoefeqi,lexo]=eqlist(eq,coef)
eq = a string of the form : 'varendo=coefi*varex1+ +coefj*varexk' with varexi possibly lacking
coef = a string vector of the form coef=['coef1'; ;'coefn']
namey = the name of the rhs variable
ncoefeqi = a (nx1) vector of the indexes of coefi, ,coefj in coef
lexo = a (nx1) vector of names of the exogenous variables