Support UTF8, different currency, no shipping & hidden reference info

The plugin fit exactly to what I needed to integrating paypal into my website, but some features were missing, so I added them myself.
I thought it would be nice if it’s added to the addon, then I won’t need to fork from it.

1. I’ve integrated the addon in a non-english website (Hebrew). When passed to paypal, the Hebrew text became Gibberish due to missing UTF-8 parameter.
Add (should always be added): <INPUT TYPE=”hidden” name=”charset” value=”utf-8″ />

2. No need for shipping address in my website, so can skip that too.
Add (can be added as a shortcode parameter): <input type=”hidden” name=”no_shipping” value=”1″ />

3. To display my own currency, I added: “options_currency” parameter to pass the currency string to attach to the price in options list.

4. I integrated the plugin using PHP, so already had the reference info I wanted to pass to paypal. I added a parameter “hidden_reference” that will just pass the value without an input box.

Full PHP code is available here: https://pastebin.com/GJmb7K0b

Would be happy to hear comments about the changes.

https://www.ads-software.com/plugins/wordpress-easy-paypal-payment-or-donation-accept-plugin/