previously, the only way to get numeric matching was with the
range operators :> :>= :< :<=
now, when we encounter field:val if the val can be parsed as a
number, then we do a disjunction search, which includes
searching for val as a text term and as an exact numeric value
1) disjunction and conjunction queries now support a
"query string mode". By default they do not operate
in this mode. When in this mode, any disjunct/conjunct
which evaluates to MatchNone searcher, will be removed
from the disjunction/conjunction. If the query ends
up with NO conjuncts/disjuncts, it will itself
return the MatchNone seacher.
2) boolean query also supports a query string mode. when in
this mode, the Must, Should and MustNot searchers are all put
into query string mode.
3) rewriting of negation only queries (like -foo) now take into
account the rewriting rules above, and those are handled first.
this means that we rewrite correctly in case of +stoword -foo
4) the empty query string is now valid, and returns 0 hits.
previously this was considered a validation error.
as we are a Go library is this the much more natural way to
express such queries.
support for strings is still supported through json marshal
and unmarshal, as well as inside query string queries
as before we use the package level QueryDateTimeParser to
deterimine which date time parser to use for parsing
only serializing out to json, we consult a new package
variable: QueryDateTimeFormat
this addresses the longstanding PR #255
Boostable, Fieldable, Validatable broken out into separate
interfaces. This allows them to be discoverable when
needed, but ignorable otherwise. The top-level bleve package
only every cares about Validatable and even that is optional.
Also, this change goes further to make the structure names
more reasonable, for cases where you're directly interacting
with the structures.
