debugger: breakpoints in scripts not loaded yet.

This pull requests allows users of `node debug` CLI to set a breakpoint
in a file (module) that was not loaded yet.

When developer calls setBreakpoint with an unknown script name,
we convert the script name into regular expression matching all
paths ending with given name (name can be a relative path too).

To create such breakpoint in V8, we use type `scriptRegEx`
instead of `script` for `setbreakpoint` request.

To restore such breakpoint, we save the original script name
send by the user. We use this original name to set (restore)
breakpoint in the new child process.