Plugin utilities: Moved encoding guesser to header

Moved the string encoding guesser/converter to the Plugin.h header, so
it may be accessible from any plugin. I may make it a global member of
something eventually, but a static inline for such a simple function
should be fine for now.

This function facilitates converting arbitrary 8 bit encoded strings to
Unicode NSString objects. It should be used anywhere that UTF-8 is
expected, but not necessarily guaranteed, and where other 8-bit
encodings may also be supplied by a user's files.

Not using this setup for string inputs has already led to failed UTF-8
decoding resulting in nil NSStrings being passed to the inline array or
dictionary initializers, which results in crashes due to uncaught
exceptions.

Signed-off-by: Christopher Snowhill <kode54@gmail.com>

Audio/Plugin.h

@@ -98,3 +98,10 @@
 
 - (int)putMetadataInURL:(NSURL *)url;
 @end
+
+static NSString *guess_encoding_of_string(const char *input) {
+	NSString *ret = @"";
+	NSData *stringData = [NSData dataWithBytes:input length:strlen(input)];
+	[NSString stringEncodingForData:stringData encodingOptions:nil convertedString:&ret usedLossyConversion:nil];
+	return ret;
+}

Plugins/HTTPSource/HTTPSource.m

@@ -59,13 +59,6 @@ static size_t http_curl_write_wrapper(HTTPSource *fp, void *ptr, size_t size) {
 	return size - avail;
 }
 
-static NSString *guess_encoding_of_string(const char *input) {
-	NSString *ret = @"";
-	NSData *stringData = [NSData dataWithBytes:input length:strlen(input)];
-	[NSString stringEncodingForData:stringData encodingOptions:nil convertedString:&ret usedLossyConversion:nil];
-	return ret;
-}
-
 static int http_parse_shoutcast_meta(HTTPSource *fp, const char *meta, size_t size) {
 	//    DLog (@"reading %d bytes of metadata\n", size);
 	DLog(@"%s", meta);