LONDON, March 6 (Reuters) - European stocks are seen slightly softer at the open on Wednesday as investors lock in some profits on the previous session's jump to multiyear highs and nervousness creeps in ahead of key central bank meetings and data due this week. At 0715 GMT, futures for Euro STOXX 50 fell 0.2 percent, while those for Germany's DAX and France's CAC were both 0.1 percent lower. Futures for Britain's FTSE 100, however, added 0.1 percent. "There could be an element of cautio