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