Fix file tree merging (broken since 7b26d6b3)

fix generated provides of files provided by more than one package

(uniqueify_properties() assumes that each property only belongs to a
single package, so our previous strategy of generating a single property
with an indirect package list wouldn't work.)

fix the types of fields in razor_property for easier debugging

also fix a case in razor_transaction_describe

update to deal with obsoletes better

when looking for a package "foo" to install/update, we have to look
not just for a package named "foo", but also any package that
obsoletes+provides "foo".

So redo the algorithm to satisfy *all* installs/removes from the
property list, so now we don't need to walk the package list at all.

update to match DEPSOLVE.txt

unfortunately not quite right; it can't figure out that "git-core" updates
to "git"

when importing, create fake file PROVIDES to match file REQUIRES

update DEPSOLVE.txt after talking with Kristian

In particular, we're going to do the fake PROVIDES for files thing now.

depsolving plan

Fix both sides of provide/conflict handling to work the same way

thus fixing conflicts-on-properties-rather-than-names, thus fixing the
last remaining unpassed test

kill warning