Case T-631/15: Judgment of the General Court of 13 December 2018 — Stena Line Scandinavia v Commission (State aid — Public financing of the Fehmarn Belt fixed link rail-road project — Individual aid — Decision not to raise any objections — Decision finding no State aid and declaring the aid compatible with the internal market — Definition of State aid — Adverse effect on competition and effect on trade between Member States — Conditions governing compatibility — Aid to promote the execution of an important project of common European interest — Necessity of the aid — Incentive effect — Proportionality of the aid — Serious difficulties justifying the initiation of the formal investigation procedure — Obligation to state reasons — Communication on State aid to promote the execution of important projects of common European interest)