Fix Problem::var_type (continuous variables precede integer).
Add an AMPL file declaring the icl suffix and its possible values.
Implement the icl suffic. Add the restart option.
Initialize suffix.
Mention suffix icl in README.
Move WriteExpr to expr.h.
Fix a warning.
Update gecode.
Update the format library.
Add missing include.
Update the format library.
Add support for restart-based search in gecode.
Fix a warning.
Add IsZero.
Implement WriteExpr. Rename Expr::opname to Expr::opstr.
Implement WriteExpr for logical expressions.
Implement ExprWriter. Rename PiecewiseLinearTerm to PiecewiseLinearExpr for consistency.
Update gsl to version 1.16
Add .travis.yml
Change build script