support multiple plugin parameters and names on CLI

This pull request combines #474 and #476 as discussed in #473.
However, I don't like this too much because of the following reasons:
1. ec_strtok uses strtok_r but can fall back to it's unsafer variant strtok.
2. checking the '*list*' plugin has to done twice (*without special pattern matching*)
3. the freeing of the temporary variable isn't yet thread safe (*because not yet threading at that stage*)

I'd feel better if we would go for #476 with one plugin name as argument of the **-P** switch.