Translations can receive arguments

Translations are able to receive unlimited number of arguments.

Given the translation file:
```
greetings = Hi, %s.
myname = My first name is %s, and my last name is %s.
thisWorksAsWell = Handy I think!
```
and following PHP code:
```
$name = "Stefan";
$last = "Crnjakovic";

echo L::greetings($name);
echo L::myname($name, $lastname);
echo L::thisWorksAsWell;
```
output would look like this:
```
Hi, Stefan.
My first name is Stefan, and my last name is Crnjakovic.
Handy I think!
```