aMBITIOUS plans have been unveiled to transform the mothballed Nigg fabrication yard on the Cromarty Firth into a service hub for the energy industry.  The announcement, which includes a pledge to create 2,000 jobs in the next four years, was hailed by First Minister alex Salmond as marking the "potential renaissance of marine engineering in the Highlands". He promised GBP 1.8 million of government funding to help kick-start the revival of a yard that once had a workforce of 5,000 and was worth GBP 100m a year to the Scottish economy.  Major work at the yard effectively ceased in 2000 and the 238-acre site has been lying dormant since 2003.  It was first offered for sale in 2005 by american engineering giant KBR and the Wakelyn trust, which owns part of the site.  It was confirmed yesterday the site has now been bought for an undisclosed sum by Inverness.-based company Global Energy Group, which plans to turn