enh: big clean
enh: big clean

- rewrote partially NRPE class.
- simpler logic (somehow: less code, simpler main loop, etc..)
- more robust: close() in set_exit()
- clean and better comments

staute/shinken-mod-booster-nrpe,staute/shinken-mod-booster-nrpe,k0ste/mod-booster-nrpe,pombredanne/mod-booster-nrpe,k0ste/mod-booster-nrpe,pombredanne/mod-booster-nrpe,shinken-monitoring/mod-booster-nrpe,shinken-monitoring/mod-booster-nrpe