Add Support for roche 5800

[aurthurm]

To add support for roche 5800 we need to check if sampleNumber == len of obx and subtract 1 from index
I suggest to use the following:

       let index = (sampleNumber * 2) - 1

        // Index access error if:
        // index == 1 when sampleNumer == 1 and obx.length == 1
        // Therefore we reduce index by 1
        if(index >= obx.length) {
          index-=1
        }

        let singleObx = obx[index]; // there are twice as many OBX .. so we take the even number - 1 OBX for each SPM

@amitdugar

[amitdugar]

Thanks @aurthurm

I have merged your Pull Request