Fixed parse failure on Choice trees with only a single child/value & (Multi)Lists with only a single Item/value.
Both scenarios are now supported by means of changes to IntegerColumn & IntegerRangeMapping, which now support having a 0-bit size (i.e. now actual bits are used to store/transmit the one and only value they can take).
Also made various related/other improvements to IntegerColumn, IntegerRangeMapping (now completely based on BigInteger to support integers of beyond 64 bits), BitInputStream & BitOutputStream + new BigIntegerUtils class.

Signed-off-by: Matthias Stevens <matthias.stevens@gmail.com>
Merge branch 'master' of github.com:ExCiteS/Sapelli
Added virtual "Caption" column for ChoiceField

Signed-off-by: Matthias Stevens <matthias.stevens@gmail.com>