Import upstream Diehard4 by obscurant

Verbatim contents of the upstream GitHub archive (Diehard4-master.zip,
commit 254ee204deebc64793123a9643c85b7d113c6c22, files dated 2019-05-21).

Imported unmodified so that every change in this fork is visible as a diff
against the original, which is what GPL-3.0 section 5(a) is asking for.
All code in this commit is obscurant's work, not mine.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

openbox-3/shade.xbm

@@ -0,0 +1,5 @@
+#define shade_width 11
+#define shade_height 11
+static unsigned char shade_bits[] = {
+   0x01, 0x04, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x88, 0x00, 0xd8, 0x00,
+   0x70, 0x00, 0x20, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x04 };