Feature/wasm js demo (#191)

* Moved `nym-sphinx-wasm` into `wasm` folder and renamed its examples

* A proposal for some structural cleanup

* desktop client: beginning of a Rust example for chunking.

* Simplifying desktop client readme

* Tarting up webassembly README

* A more visual webassembly client example

* clients/webassembly: grouping a few things into named functions for clarity

* clients/webassembly: put URLs at top of file, prepping for drop-down action

* mixnode + provider run: changed startup error messages a bit

* clients/webassembly: scrolling from the bottom in the demo

mixnode/src/node/mod.rs

@@ -130,7 +130,7 @@ impl MixNode {
 
         if let Some(duplicate_node_key) = self.check_if_same_ip_node_exists() {
             error!(
-                "Our announce-host is identical to one of existing nodes! (its key is {:?}",
+                "Our announce-host is identical to an existing node's announce-host! (its key is {:?}",
                 duplicate_node_key
             );
             return;