+ add pkgname parsing
+ handle package conflicts
+ handle package dependencies to the level of the old implementation
+ handle chmod/chown to the level of the old implementation
+ handle PKGPATH
+ replace symlinks with @symlink commands at pkg_create time
+ basic validation of packing list at end of reading it...
+ don't store @pkgdep in packing-lists, makes for a lot of traffic, use
separate +REQUIRE file instead. Automatically convert from the old model.
+ add better error handling
- let package delete log files it cannot delete
- smart package dependency handling

Known update issues:
- pkg_add -r can have two conflicting packages (or more) n-to-m updates
should be handled.

- switch all runtime dependencies to @newdepend.  Stuff older @libdepend
into newer @wantlib keyword.  Makes for more systematic handling (adjust
RUN_DEPENDS to take wildcard pkgspec by default as well) and allows us
to put all lib dependencies into a package: base system included.
Issue (again): converting from the old model.