Added plugins:
- time/ntp{date,dispersion,jitter,offset,stratum,wander} plots using 'ntpq -c rv' and not the deprecated ntpdate. Tested on ntpsec-1.0.1/ntpd-4.2.8p10 on OpenWrt SNAPSHOT r5638-0f72690a2d, inspired by https://www.wraith.sf.ca.us/ntp/do-ntp-rrdstats
- sensors/apu{power,temp} to plot PC Engine's APU2c4 AMD GX412-TC CPU and Phison mPCI-e mSATA SSD temps
TODO: Use ntpd statistic files {clock,loop,peer}stats to plot clock/frequency offsets and refclock/peer jitter instead of ntpq