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.cpp

@@ -24,7 +24,7 @@ NACT::NACT(int sys_ver, uint32 crc32_a, uint32 crc32_b, const Config& config)
 	  crc32_a(crc32_a),
 	  crc32_b(crc32_b),
 	  lang(get_language()),
-	  encoding(Encoding::create())
+	  encoding(Encoding::create(get_encoding_name(config)))
 {
 	platform_initialize();
 

src/sys/nact.h

@@ -258,6 +258,7 @@ public:
 	static const int get_sys_ver(uint32 crc32_a, uint32 crc32_b);
 	const char* get_title();
 	Language get_language();
+	const char* get_encoding_name(const Config& config);
 	void text_wait();
 	void set_skip_menu_state(bool enabled, bool checked);
 

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";
+}