Refactored voltageMonitor module as a class with a singleton instance

- voltageMonitor_module (.h/.cpp) has been refactored to a class
VoltageMonitor (.h/.cpp), with a singleton instance called
VOLTAGE_MONITOR
- useless (empty) function initVoltageMonitor has been removed
- application code has been modified according to this refactoring
- project properties have also been modified
Refactored rtc module as a class 

- rtc_module (.h/.cpp) has been refactored to a class
DS1302_RTC (.h/.cpp), subclass of DS1302
- useless (empty) function initRTC has been removed
- application code has been modified according to this refactoring
- project properties have also been modified
Refactored leds module as classes 

- Led class allow to handle a single LED (on/off, blink)
- Leds class allow to handle a group of LEDs (on/off, blink)
- application code has been modified according to this refactoring
- project properties have also been modified
Renamed constants in pins.h

- Pins-related constants are now suffixed with "_PIN"
- Channels-related constants are now suffixed with "_CHANNEL"

- application code modified according to this refactoring
Refactored logging module as a class with a singleton instance

- logging_module (.h/.cpp) has been refactored to a class
Logger (.h/.cpp), with a singleton instance called
LOGGER
- application code has been modified according to this refactoring
Cleaned project properties	

- Inner project object files have been removed from linker settings, as
they seem to be useless
Cleaned #include in Logger and Led modules

- removed useless #include
Refactored analog sensors module as classes 

- AnalogSensor class allow to handle a single analog sensor (read)
- AnalogSensors class allow to handle a group of analog sensors (read)
- application code has been modified according to this refactoring
Updated LED visual notoifications
Modified read implementation in AnalogSensors

- implementation is now really independent of sensors amount
Partially added persistant (EEPROM) integer counters support

- Counter (.h/.cpp) allows to handle a single persistant counter (read,
set, increment). THIS CLASS IS A SKELETON TO BE COMPLETED
- Counters (.h/.cpp) allows to handle all counters (read)

- declared counters base addresses in defs.h as #define
- added counters support in customFrameBuilder and application code
Fixed a bug in Logger

- logMessage now returns correct status
Updated LED visual notifications