chore(core,lib): add #pragma once to header files

include/core.h

@@ -1,6 +1,7 @@
 // Tanabata file manager core lib
 // By Masahiko AMANO aka H1K0
 
+#pragma once
 #ifndef TANABATA_CORE_H
 #define TANABATA_CORE_H
 

include/tanabata.h

@@ -1,6 +1,7 @@
 // Tanabata file manager lib
 // By Masahiko AMANO aka H1K0
 
+#pragma once
 #ifndef TANABATA_H
 #define TANABATA_H