string/interp can't handle strings composed with str

[jmglov]

It would be nice to be able to build up long strings for interpolation like so:

(let [foo 1
      bar :baz]
  (string/interp (str "foo: $foo$" ", bar: $bar$")))

However, it throws the following error:

ERROR: 
 in pixie function repl_fn

in pixie/repl.pxi at 27:24
               (let [x (eval form)]
                       ^
in internal function eval

in pixie function interp

in /home/jmglov/Documents/code/pixie/pixie/string.pxi at 120:7
      (starts-with? txt "$")
      ^
in internal function starts-with

in internal function name

in polymorphic function -name dispatching on pixie.stdlib.Cons

RuntimeException: :pixie.stdlib/AssertionException No override for pixie.stdlib.Cons on -name in protocol INamed

[jmglov]

I think we should simply remove string/interp once we've resolved #444. Closing this.