Fixed the debugger client to work in Eclipse 3.1.

Fixed the debugger client to work in Eclipse 3.1.
The method of integration of the debugger model into the debugger view appears to have changed from 3.0 to 3.1. I added implementations of
getAdapter() for PHPDebugTarget and PHPThread to properly add Launch
(e.g. Debug) View tree nodes for targets, threads and stack frames.

Fixed a live leak resulting from PHPDebugTarget not deregistering itself from
listening to breakpoint and debug events.

Added utility log methods to net.sourceforge.phpeclipse.PHPeclipsePlugin.