Split into multiple files

For multiple reasons the program is now split:
- Make future porting to OpenBSD easier
- Assign header includes to individiual functions
- Make future program extensions easier
- Recompile only changed parts

temperature.c

@@ -0,0 +1,12 @@
+#include <stdio.h>
+
+#include "util.h"
+
+const char *
+temp(const char *file)
+{
+	int temp;
+
+	return (pscanf(file, "%d", &temp) == 1) ?
+	       bprintf("%d", temp / 1000) : NULL;
+}