Devel extended logging

If you're a "tail -f" kind of debugger, you may find this module useful. It adds a number of functions that write to the debug log file:

- ddi(): Indents debug messages based on the depth of the call stack
- dds(): Logs just the attribute/key names of an object/array.
- ddb(): Logs just the function names from the debug_backtrace() function call stack
- ddf(): Logs the name of the current function, indented with ddi()
- ddu(): Logs a message and moves cursor one line up
- ddt(): Writes debug messages with code execution timestamps included

See the function comment blocks for full documentation.

Version 1.2 introduces ddon() and ddoff(). These functions globally toggle all the debug function on and off.