Functions to move to splitstackshape

- [ ] CBIND
- [ ] RBIND
- [ ] table2df ?
- [ ] multi.freq.table ?

`table2df` is more of a `data.frame` utility, so less applicable to the "splitstackshape" package. `multi.freq.table` is more of an "aggregation" function, so also less applicable to "splitstackshape". `CBIND` and `RBIND` are very good fits though.
