Allow deletion of multiple sites
clean up multi delete
Implement Egypt's suggestions

Delete_site input is now validated with =~ /^[0-9]*$/.
Help instructions written in English.
Remove errant return

Installing a trap for "INT" is still wrong, it should be rescuing
Interrupt instead. This is just a bandaid to keep it from crashing
msfconsole any time ctrl-c is used after running wmap_run for the first
time.
Land #1575, 'wmap_sites -d' improvements