Add read/write Config Register1

[abbat]

• Add functions for r/w Config Register1;
• Add functions for r/w FIR (noise) filter settings;
• Add functions for r/w IIR (spike) filter settings;
• Add settling time calculation based on FIR/IIR settings.

FIR/IIR filter settings described in MLX90614ESF datasheet and in "Understanding MLX90614 on-chip digital signal filters".