Two-part $Horolog is unsupported

`x,y` is a valid horolog format (x is date, y is time).
However it causes this error if present:
```
TypeError: e.split is not a function lightPivotTable.js:10:2455
getUnixDateFromCacheFormat 
renderRawData 
dataChanged 
dataIsChanged 
dataController
setData
refresh
c
e
onreadystatechange
```