Node: remove formal equals(), hash

Since Node extends Object, not Basic, it doesn’t get the default
equals() and hash implementations, so subclasses have to provide these
even if Node doesn’t explicitly declare them formal.
Format source code

But I have an excuse this time! I only just updated ceylon.formatter for
the latest language module changes.
Rename test functions (remove \i prefixes)

\i is very unceylonic and only intended for interop use, @quintesse
tells me. (The identifier() function is pretty unique, so in most cases
there won’t be a conflict between \iNodeType and nodeType anyways.)