Formula 1 legend Michael Schumacher is set to have stem cell surgery by a world-renowned doctor in a bid to regenerate his nervous system.    Schumacher hit his head while skiing in the French Alps resort of Meribel on December 29, 2013. He suffered a severe brain injury as a result.     The icon will undergo another operation in the coming days, according to Italian media reports. The operation will be performed by French professor and cardiologist Dr Philippe Menasche.    Dr Menasche is a world-renowned …