- add a [sibling] option to .PKGINFO -- used when only one of
  the siblings can be installed at a time (eg, bsdinit,sysvinit)
- sort packages by package name in pacman.db
? manage conditional file installs (ie, 'info' pages)
- maybe add a 'confirm every action' option for doing paranoid installs
- add a consistency check operation
- add file locking to db
- add a --dbpath option
+ dependency checking
- upgrade currently does a double db backup; not really desirable