Converts a list of (name, kind, what) tuples to a match dict. Where name is the field to match, kind is a matchable number mapping to CONST_TO_MATCHABLE.
Probably best explained by an example:
>>> mtuplelist = [("name", CONDITION_ENDSWITH, "Constanza"),
... ("zipcode", CONDITION_STARTSWITH, "70")]
>>> mtuplelist_to_matchdict(mtuplelist)
{"name": Endswith("Constanza"), "zipcode": Startswith("70")}