Add generic int16_t fields to radio packet data structure

[jgc]

• Add 3 generic int16_1 fields to the radio packet structure to support e.g. current temp, max and min
• Adding 4th to handle e.g. light sensor and / or motion sensor in same transmission.

jgc/falco_sw_photon#1

[jgc]

typedef struct {
uint8_t node;
uint8_t tran;
int16_t batt; // battery voltage in millivolts
int16_t value1; // Generic e.g. Current temperature in dec * 100
int16_t value2; // Generic e.g. Minimum temperature in dec * 100
int16_t value3; // Generic e.g. Maximum temperature in dec * 100
int16_t value4; // Generic
} Payload;
Payload theData;

TBC: LImit is 12 bytes