Get the stack order correct
comment out some debugging prints
forgot to use strict/warnings
Make the debugging prints clearer
The debugger window will now render the initial stack and program code
stack tabs now have shorter labels and include tooltips with more info
refactor to remove the source_file() method
make single-step turn on $DB::single
DB::DB returns immediately unless there's a breakpoint of some kind
style sheet for the debugger
typo: can't have multiple "class" attribs
improve look of code window

removes the divider between rows
The step-in button is working

The code window highlites the currently active line, but doesn't remove the
highlite from the previous line (yet)