made pkgman cleanly remove packages before updating them

lib/pkgman.lua

@@ -128,6 +128,7 @@ function pkg.upgrade(force) -- boolean -- boolean -- Upgrades all packages on th
  for repo,info in pairs(getSources()) do
   for pkgname,pkg in pairs(getRepoMeta(repo)) do
    if pkg.version ~= installed[pkgname].version or force then
+    pkg.remove(pkgname)
     dl(info.path.."/"..pkg.filename,"/boot/pkg/"..pkg.filename)
     installed[pkgname] = pkg
     pcall(activatePackage,"/boot/pkg/"..pkg.filename,pkg.compressed)