Space optimization and RDS improvements

Support to the advanced features of the SI474X devices
More examples and code optimization
This is an Arduino library for the SI47XX, BROADCAST AM/FM/SW RADIO RECEIVER IC family from Silicon Labs. This library is intended to provide an easier interface for controlling the SI47XX by using Arduino platform. Features:
FM (VHF) support (64–108 MHz);
AM (MW) band support (520–1710 kHz);
SW band support (2.3–26.1 MHz);
LW band support (153–279 kHz);
Allows firmware upgrade. Including the possibility of adjustments to demodulate SSB;
Advanced AM/FM seek tuning;
Automatic frequency control (AFC);
Automatic gain control (AGC);
Digital FM stereo decoder;
AM/FM/SW/LW digital tuning;
RDS/RBDS processor;
Digital audio out;
I²C and SPI interface;
More than 120 Si47XX function implemented;
Bluetooth Remote control examples;
EEPROM support (See examples)