Remove explicit creation of sig file, gnupload script handles that

[matsl]

What

• Makefile (package): Depend on tar-file.
  (release): Remove targets not needed.
  (git-pull): Make check robust for current state on the workfolder.
  (git-tag-release):
  (ftp): Add confirm check for these potential dangerous targets.
  ($(pkg_parent)/hyperbole-$(HYPB_VERSION).tar.gz): Add dependency on
  tar file.
  ($(pkg_parent)/hyperbole-$(HYPB_VERSION).tar.sig): Remove
  target. gnupload script handles the sig file.
  (packageclean): Simplify cleanup by removing whole package build
  directory.
  (GNUFTP): Add --dry-run during for now while testing.

Why

gpg signature is not needed. gnupload script handles that and we can
skip that step.

While at it some unused or not needed parts of the Makefile was
removed.

Safety confirmations steps where added to the git-tag-relase and ftp
target as they could cause issues if executed by mistake.

In this first PR the --dry-run option is set on gnupload script as
well as an extra precaution to allow testing of the ftp target.

Note

When we do the release it would be good to do that together so we can
fix any issues. But it should now be possible for testing purposes to
run things like:

    make package
    make packageclean
    make ftp