Enable all warnings, turn the noisy ones back off, fix the others.

src/connection_win.cpp

@@ -9,7 +9,7 @@
 
 int GetProcessId()
 {
-    return ::GetCurrentProcessId();
+    return (int)::GetCurrentProcessId();
 }
 
 struct BaseConnectionWin : public BaseConnection {
@@ -125,4 +125,4 @@ bool BaseConnection::Read(void* data, size_t length)
         Close();
     }
     return false;
-}
+}