PARIS (Reuters) - The Paris region opened its bus system to competition on Wednesday, kicking off the liberalisation of one of Europe's biggest public transport systems.The board of regional public transport authority Ile-de-France Mobilites (IDFM) approved a new system for private operation of parts of its bus system and selected the first routes to be opened for a series of tenders that will be worth more than 12 billion euros (£10 billion).The Ile-de-France region - which accounts for about..