debug: Split DebugTools.st into multiple files

Split debug tools package using the one class one file pattern.

2013-08-20  Gwenael Casaccio <gwenael.casaccio@gmail.com>

	* DebugTools.st: Split DebugTools file.
	* Extensions.st: New.
	* DebuggerReentered.st: New.
debug: Add new command for printing context state

2013-08-20  Gwenael Casaccio <gwenael.casaccio@gmail.com>

	* MiniDebugger.st: Add new command for printing context state.