How to replace placeholders with actual values?
<p>I need a function that replace every variable_name inside '{}' with the correct variable. 
Something like this:</p>

<pre><code>$data["name"] = "Johnny";
$data["age"] = "20";

$string = "Hello my name is {name} and I'm {age} years old.";

$output = replace($string, $data);
echo $output;

//outputs: Hello my name is Johnny and I'm 20 years old.
</code></pre>

<p>I know there are framework/engines for this, but I don't want to have to install a bunch of files just for this.</p>
