[perl5db] Extract a method.
Refactoring - convert $trace to our.
[perl5db] Convert variables to our.

This helps avoid calling them with $DB::var_name.
[perl5db] Convert more global vars to our.
More variables to our.
Placed declarations on one line and sorted.
$slave_editor → our.
Fix "a [command]" statement.

Without a line number. See:

https://rt.perl.org/rt3/Ticket/Display.html?id=115110 .
Extract _handle_S_command.
Extract _handle_V_command_and_X_command.
Extract _DB__handle_f_command.
[perl5db] Extract another function.
[perl5db] Extract $obj->_handle_dash_command.
Extract _DB__handle_y_command .
[perl5db] Extract _handle_n_command.
Extract _handle_s_command and refactored.
[perl5db] Extract _handle_c_command.
[perl5db] Extract _handle_r_command.
Extract _handle_T_command.
Extract _handle_w_command.