Merge branch 'ah/commit-id-to-clipboard'

* ah/commit-id-to-clipboard: gitk: offer "Copy commit ID to X11 selection" only on X11 gitk: support auto-copy comit ID to primary clipboard gitk: prefs dialog: refine Auto-select UI gitk: UI text: change "SHA1 ID" to "Commit ID" Signed-off-by: Johannes Sixt <j6t@kdbg.org>