Fix Room v3 Issue

This at least partially addresses #3.  I have a feeling that
additional updates will be needed at some point, but this
fixes the issue where mtxclient would throw an exception for
unrecognized event id formats, which caused nheko to crash.

include/mtx/identifiers.hpp

@@ -90,7 +90,10 @@ parse(const std::string &id)
                 identifier.hostname_  = id.substr(parts + 1);
                 identifier.id_        = id;
         } else {
-                throw std::invalid_argument(id + ": invalid format\n");
+                // V3 event ids don't use ':' at all, don't parse them the same way.
+                identifier.localpart_ = id;
+                identifier.hostname_ = id;
+                identifier.id_ = id;
         }
 
         return identifier;