splittable, like [term1,term2] was transformed into a phrase search, which
made sense in some cases, but no so many. This commit changes this:
[term1,term2] now means term1 AND term2. [term1/term2] means
term1 OR term2. This is especially useful for field searches where you
would previously be forced to repeat the field name for every term.
[somefield:term1 somefield:term2] can now be expressed as somefield:term1,term2
