fixed EXPLAIN attempts in PhpQuickProfiler

Explain was always using default DB connection - fixed it, and also fixed indentation in get_cursor().

P.S. Already asked in twitter, will repost the question here - what happens with 1.8/develop fixes, considering that 1.7 is final? 1.7.x, or what?

upd: got it, waiting for 1.7.1 :)