Performance improvements for rp_filter and parameter:
- improve performance of rp_filter (which is run on every
   non-resources request) significantly (often a factor of 2)
- improve scalability by reducing number of required mutex locks
  (e.g. for secret token handling)
- get rid of  "global" statements
- use "unset -nocomplain ..." instead of exists test
- use absolute name to avoid namespace confusions