- exprValueFieldTag is an extended version of exprValue,
with additional Field/List uniformity handling
- the exprValueFieldTag reduce() method provides a more efficient
method than using a regular combine operator. Since fields are
usually non-uniform, will mostly only need the bitwise reduce and
not a more expensive gather/combine.
ENH: output of exprValue (scalar type) now includes '.'
- prevents scalar/label ambiguity for values like '100.0', which would
otherwise be written as '100' and thus interpreted as a label value
when re-reading.
