Oil markets breathed a sigh of relief on Tuesday amid tentative signs that the global glut of crude was being drained. Brent crude, the Middle East benchmark, traded above $30 a barrel for the first time since the middle of last month. It rose by $3.77, or 13.9 percent, to close at $30.97 a barrel. West Texas Intermediate, the US standard that collapsed into negative territory last month, gained $4.17 ...