bashrc: implement `perlbrew (use|switch) (system|default)`
bashrc: implement `perlbrew (use|switch) (system|default)`

Asuza/App-perlbrew,calid/App-perlbrew,rafl/App-perlbrew,dagolden/App-perlbrew,ptolemarch/App-perlbrew,Asuza/App-perlbrew,ptolemarch/App-perlbrew,Asuza/App-perlbrew,rafl/App-perlbrew,rafl/App-perlbrew,josl/App-perlbrew,dagolden/App-perlbrew,calid/App-perlbrew,ptolemarch/App-perlbrew,josl/App-perlbrew,josl/App-perlbrew