Fix score evaluation for multiple values in properties

Sometimes fonts has multiple values in family and sub-family in order to unify other variants into one. they basically make difference in sub-family though, they also still have standalone family and sub-family. in that case, sub-family is likely to be Regular.

fontconfig couldn't recognize the difference between :family=Foo:style=Regular and :family=Foo Caption:style=Regular for example because fontconfig didn't give different score on matching result for the position of multiple values in a cache. Thus, when querying a font like :family=Foo:style=Regular may results :family=Foo Caption:style=Regular. (see the test case for more details)

To fix this situation, giving different score according to the position of multiple values in a cache as well as the position of multiple values in a query.

Fixes #283 (closed)