global: do not offer the renice option, let's the user handle that

It's broken anyway. Eg.:
- user is already niced at 10
- user configures to renice at 5
- breaks because user is not allowed to 'boost' his/her nice value

Bette let the user handle the renice with:
nice -XX ct-ng 'action'

 #!/bin/sh

 SKIP_ME="### CT_NG SKIP ME ###"

 skip_me=$(($(cat "${0}" |@@grep@@ --binary-files=text -o -b -E "^${SKIP_ME}$" |cut -d : -f 1)+${#SKIP_ME}+1))

 dd if="${0}" bs=${skip_me} skip=1 2>/dev/null |bzcat

 exit 0

 ### CT_NG SKIP ME ###