json: Switch to gason instead of vjson.

From the same author.  Most importantly, reads numbers as doubles rather
than as signed ints and floats.  This allows us to actually read 32 bit
unsigned int parameters.

Moved all the native customization to a separate json_reader.cpp.

UI/RemoteISOScreen.cpp

@@ -21,9 +21,9 @@
 #include <condition_variable>
 
 #include "base/timeutil.h"
-#include "ext/vjson/json.h"
 #include "file/fd_util.h"
 #include "i18n/i18n.h"
+#include "json/json_reader.h"
 #include "net/http_client.h"
 #include "net/http_server.h"
 #include "net/resolve.h"
@@ -252,16 +252,19 @@ static bool FindServer(std::string &resultHost, int &resultPort) {
 		return false;
 	}
 
-	const json_value *entries = reader.root();
-	if (!entries) {
+	const JsonValue entries = reader.rootArray();
+	if (entries.getTag() != JSON_ARRAY) {
 		return false;
 	}
 
 	std::vector<std::string> servers;
-	const json_value *entry = entries->first_child;
-	while (entry && !scanCancelled) {
-		const char *host = entry->getString("ip", "");
-		int port = entry->getInt("p", 0);
+	for (const auto pentry : entries) {
+		JsonGet entry = pentry->value;
+		if (scanCancelled)
+			return false;
+
+		const char *host = entry.getString("ip", "");
+		int port = entry.getInt("p", 0);
 
 		char url[1024] = {};
 		snprintf(url, sizeof(url), "http://%s:%d", host, port);
@@ -270,8 +273,6 @@ static bool FindServer(std::string &resultHost, int &resultPort) {
 		if (TryServer(host, port)) {
 			return true;
 		}
-
-		entry = entry->next_sibling;
 	}
 
 	// None of the local IPs were reachable.