GnuTLS: use gnutls_transport_set_int if available

gnutls_transport_set_ptr may cause problems on some platforms,
therefore the replacement gnutls_transport_set_int is used
when available (since GnuTLS >= 3.1.9).
GnuTLS: check for required function

added a check for function gnutls_cipher_init (GnuTLS >= 2.10.0).
Without it, Bareos will fail to build with GnuTLS,
therefore GnuTLS will be disabled.
recreated configure
Windows Installer Overhaul

- Database Setup is now done by the installer itself
- Added database dialog for that
- Interactively the administrator login is directly checked
  and installation cannot go on if administrative account cannot login
- Added logging functions to better be able to debug installer
  Variable $WriteLogs is used for that.
- Debug installer always writes logs
- Passwords for psql login are transferred in environment variables, no
  passwords are written to files.
- Help text if called with /? now really is the first done.
- If silent installer aborts, it writes a file "abortreason" to $TEMP
- Installer Parameters added:
  - /INSTALLDIRECTOR select director section for install
    this also selects bconsole section
  - /INSTALLSTORAGE selects storage section for install
  - /DBADMINUSER=<user> sets the database admin user,
    default=postgres
  - /DBADMINPASSWORD=<password> sets the database admin password
    default=<empty>
    DBADMINUSER and DBADMINPASSWORD are used to create the bareos
    databases. If login is not possible silent installer will abort
  - /WRITELOGS makes also non-debug installer write logs
Fix typo.