Render JSON content as plain text

Some website endpoints return information in JSON, which is helpful to
be read as plain text in some situations. The content can still be
downloaded to disk using the save button or the context menu.

An example is the following endpoint https://tls.browserleaks.com/tls,
which provides TLS fingerprinting information in JSON, which will change
when reloading the page (only when Dillo is linked with LibreSSL).

The original page https://tls.browserleaks.com/ uses JS and cannot be
used in Dillo.

See: https://lists.mailman3.com/hyperkitty/list/[email protected]/message/6C5K4F6NBRUDSPNPWTXLQXCK3U3SI7DM/

ChangeLog

@@ -14,6 +14,7 @@ dillo-3.2.0 [Not released yet]
    Fix segfault when clicking the "Done" button in downloads dialog.
    Add zoom support using Ctrl +/-/0 and the "zoom_factor" option.
    Fix wrong redirect by meta refresh without URL.
+   Display JSON as plain text.
    Patches: Rodrigo Arias Mallo
 
 dillo-3.1.1 [Jun 8, 2024]

src/IO/mime.c

@@ -2,6 +2,7 @@
  * File: mime.c
  *
  * Copyright (C) 2000-2007 Jorge Arellano Cid <[email protected]>
+ * Copyright (C) 2024 Rodrigo Arias Mallo <[email protected]>
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -109,6 +110,7 @@ void a_Mime_init()
 #endif
    Mime_add_minor_type("text/html", a_Html_text);
    Mime_add_minor_type("application/xhtml+xml", a_Html_text);
+   Mime_add_minor_type("application/json", a_Plain_text);
 
    /* Add a major type to handle all the text stuff */
    Mime_add_major_type("text", a_Plain_text);