Add overlay for dmenu

Configure my own color scheme.

overlays/dmenu/default.nix

@@ -0,0 +1,7 @@
+self: super: {
+  dmenu = super.dmenu.overrideAttrs( oa: {
+    patches = [
+      ./settings.patch
+    ];
+  });
+}

overlays/dmenu/settings.patch

@@ -0,0 +1,19 @@
+--- a/config.def.h
++++ b/config.def.h
+@@ -4,13 +4,13 @@
+ static int topbar = 1;                      /* -b  option; if 0, dmenu appears at bottom     */
+ /* -fn option overrides fonts[0]; default X11 font or font set */
+ static const char *fonts[] = {
+-	"monospace:size=10"
++	"Monospace-12:bold"
+ };
+ static const char *prompt      = NULL;      /* -p  option; prompt to the left of input field */
+ static const char *colors[SchemeLast][2] = {
+ 	/*     fg         bg       */
+-	[SchemeNorm] = { "#bbbbbb", "#222222" },
+-	[SchemeSel] = { "#eeeeee", "#005577" },
++	[SchemeNorm] = { "#D3D7CF", "#2E3436" },
++	[SchemeSel] = { "#F7F7F7", "#218693" },
+ 	[SchemeOut] = { "#000000", "#00ffff" },
+ };
+ /* -l option; if nonzero, dmenu uses vertical list with given number of lines */