Don't load source Enbugger and its sub-modules

The merge has *Enbugger* not to run load_source on *Enbugger.pm* or any of its sub-modules. This could be done in *perl5db.pl* as well, although this patch doesn't do that. 

To get a sense of how many extraneous files files are loaded even with perl5db.pl put a *print* statement in *load_file*. 

Down the line, it would be cooler is to delay loading and make it lazy. The [feature suggested](https://github.com/jbenjore/Enbugger/issues/8) is directed towards that goal.