Add support for UTF-8 encoded scenario files

If `encoding = utf8` is specified in system3.ini, system3-sdl2 uses
UTF-8 as its multibyte character encoding. It will be used to run games
translated into non-(Japanese|English) languages.

src/sys/nact_crc32.cpp

@@ -8,6 +8,7 @@
 #include <string.h>
 #include "crc32.h"
 #include "../fileio.h"
+#include "config.h"
 
 namespace {
 
@@ -156,3 +157,12 @@ Language NACT::get_language()
 		return entry->language;
 	return JAPANESE;
 }
+
+const char* NACT::get_encoding_name(const Config& config)
+{
+	if (!config.encoding.empty())
+		return config.encoding.c_str();
+
+	// TODO: Determine encoding from crc32
+	return "Shift_JIS";
+}