Update to tcsh-6.18.00 - update sources & remove obsolte patches
    
    - Remove obsolete patches: tcsh-6.15.00-ca-color.patch,
      tcsh-6.17.00-tc-color.patch, tcsh-6.17.00-mh-color.patch,
      tcsh-6.17.00-history.patch, tcsh-6.17.00-printexitvalue.patch,
      tcsh-6.17.00-testsuite.patch, tcsh-6.17.00-negative_jobs.patch,
      tcsh-6.17.00-wait-intr.patch, tcsh-6.17.00-dont-set-empty-remotehost.patch,
      tcsh-6.17.00-dont-print-history-on-verbose.patch, tcsh-6.14.00-set.patch,
      tcsh-6.17.00-extrafork.patch, tcsh-6.17.00-avoid-null-cwd.patch,
      tcsh-6.17.00-avoid-infinite-loop-pendjob-xprintf.patch,
      tcsh-6.17.00-variable-names.patch,
      tcsh-6.17.00-handle-signals-before-flush.patch
      tcsh-6.17.00-status-pipeline-backquote-list-of-cmds.patch (reverted!)