load source {Perl-source-file}

Read source lines of {Perl-source-file}.

Somewhat simulates what Perl does in reading a file when debugging is turned on. We the file contents as a list of strings in _>$filename. But also entry is a dual variable. In numeric context, each entry of the list is true if that line is traceable or break-pointable (is the address of a COP instruction). In a non-numeric context, each entry is a string of the line contents including the trailing \n.