Make all getters constant?

[JohnDepaszthory]

Since the getters for CANScience were made to use getters constant, I think this should be consistent across the code base. There are a lot of getters scattered throughout that are not const.
Just one example:

int32_t DecodeTelemetryDataSigned(CANPacket *packet)
{
    return DecodeBytesToIntMSBFirst(packet->data, 4, 8);
}

uint32_t DecodeTelemetryDataUnsigned(CANPacket *packet)
{
    return (uint32_t) DecodeTelemetryDataSigned(packet);
}

uint8_t DecodeTelemetryType(CANPacket *packet)
{
    return packet->data[3];
}

In CANCommon.c. Not really a big deal but the compiler may be able to optimize better if they're declared const and every byte and cycle counts on an embedded platform