Remove unused variable
add subroutine name to the params passed to some notify methods
Add method subroutine_location()

Return file, startline, endline for the named sub
Call ->init() immediately if the debugging system is already initialized
Implement calling notify_trace() at the appropriate time
Leave the input loop if there are no ready clients
Refactor trace/follow mode

Move implementation to its own module and out of the main debugger code.