Stocks have so far this week enjoyed a slow and steady uptrend that's lifted the major indexes to fresh multiyear highs. The overall environment has been supportive for growth stocks, and a few top-rated names have executed breakouts in recent sessions. Software maker CommVault Systems (CVLT) broke out and hit a new high Thursday. Takeover talk gave CommVault a lift, according to a Bloomberg report. Spirit Airlines (SAVE) is another recent