all: FindLatestMatchingRequire takes a *Requires
yum.rpm: add sorting features for RPM
yum.rmp: Provides holds a concrete *Package (instead of RPM)
yum.rpm: Package.Release is an int
yum.xml: debug printouts
yum.xml: fix repo.xml schema+parsing
yum.xml: implement FindLatestMatchingName
yum.xml: implement FindLatestMatchingRequire
test: enable TestPackageMatching+TestPackageByNameWithRelease. add TestPackageByNameWithoutRelease+TestPackageByNameWithoutVersion