Capitalize namespacing structs

This helps to avoid name clashes when breaking up modules into packages.

src/hulk/pit.d

@@ -6,7 +6,7 @@ module hulk.pit;
 import hulk.cpu;
 import hulk.klog;
 
-struct pit
+struct Pit
 {
     /** PIT input frequency in 1/1000 Hz. */
     private enum ulong PIT_FREQUENCY_1000HZ = 1_193_181_667u;
@@ -37,6 +37,6 @@ struct pit
 
     public static void isr()
     {
-        klog.writefln("PIT ISR");
+        Klog.writefln("PIT ISR");
     }
 }