Ability to render HTML from JSON

[hasan-ozbey]

For #16

okay i've made some radical changes so take your time to analyze it.

with these changes, you'll be able to convert JSON renderer's output to any other HTML (Inline or SideBySide) renderer's output.

Here's a sample usage:

$old = "old text";
$new = "new text";
$differOptions = [ ... ];
$rendererOptions = [ ... ];

// JSON result to store in a db table
$JsonResult = DiffHelper::calculate($old, $new, 'Json', $differOptions, $rendererOptions);
----------------
// Convert it to HTML (Inline Style)
$renderer = RendererFactory::make('Inline', $rendererOptions);
$InlineResult = $renderer->renderArray(json_decode($JsonResult, true));

[jfcherng]

Thanks you. I am okay with most changes. I would like to do some tweaks and add tests but to save time, I will do it on my side after merging this.

[jfcherng]

Has been added in 6.3.0.