Inline algebraic expressions

[glebbelov]

In non-linear constraints for many solvers, the expression can have only nonlinear terms, otherwise some solvers complain.

At the moment only affects MP2NL #237 with Couenne, Conopt, CplexASl, XpressASL.

• Requires adaptation of Reference Counting Reference counting #201 .
• We can only inline if the expression result has no significant hard bounds. Example: econ2.mod. Such bounds for algebraic expressions seem to only be set in linearization of complementarity.