[Pas2js] Translating using resource strings

[Michael Van Canneyt]

Hello,

I've added a unit that presents you with an API to translate the resource
strings in your program.

The unit is called rstranslate. You can

1. Load a translation for a single resource string.

2. Load an object with a list of units/strings that must be translated in a simple format.

3. Specify an URL of a file which contains the translations.
    The file will be loaded, the object parsed and used to translate using mechanism 2.
    Since this is an async operation, there is a callback to notify you when the translation is done.

4. Reset the resource strings to their original values for one string or all strings of a unit.

For each of the cases there is a demo in the folder demo/translate.
You can click the translate button twice : every even click will reset the
translation, allowing you to switch between 2 languages.

The implementation is just a sample which should cover most use cases. 
You can perfectly create your own alternative mechanism, of course.

Still planned is to let the compiler generate a file (in the same format as
used by this API) with the default values of the strings as found in the
program source file(s).

Michael.