Add a Win32 frontend for xC

This has been more of an exercise.  The performance of Msftedit.dll
is rather abysmal, and its interface isn't the most accomodating.

That said, the frontend is quite usable, at least on Windows 10+.

xW/xW-resources.h

@@ -0,0 +1,12 @@
+#define IDI_ICON                1
+#define IDI_HIGHLIGHTED         2
+#define IDA_ACCELERATORS       10
+
+// Named after input_add_functions() in xC.
+#define ID_PREVIOUS_BUFFER     11
+#define ID_NEXT_BUFFER         12
+#define ID_SWITCH_BUFFER       13
+#define ID_GOTO_HIGHLIGHT      14
+#define ID_GOTO_ACTIVITY       15
+#define ID_TOGGLE_UNIMPORTANT  16
+#define ID_DISPLAY_FULL_LOG    17