compile: BuildOrder: properly handle local dependencies.

- Dependencies outside of the currently compiled package are still
  ignored.
- Before there was a bug that resulted in ignoring imports via
  includes.
- Use TSort from the standard library.
- It turned out that yast2-network contains dependency cycles
  between includes and modules. They can be safely broken.
yk convert - just update existing git checkout

instead of removing and downloading it again
fixups according to review: better message; Array.delete
Merge pull request #79 from lslezak/yk_update_checkout

yk convert - just update existing git checkout
updated security.patch
Make the "kerberos-server" module compile
report *which* file has an invalid byte sequence

happens with author names in latin-1 when parsing files for
dependencies
Merge pull request #80 from yast/make-kerberos-server-compile

Make the "kerberos-server" module compile
Merge pull request #81 from lslezak/security_update

Updated security.patch
Merge pull request #68 from mvidner/build-order

compile: BuildOrder: properly handle local dependencies.