Add a temporary syntax for bare functions

Bare functions will be represented as 'fn#' until they're implemented. Then
we'll switch it over to just 'fn'.

Issue #1022

src/test/run-pass/fn-bare-anon.rs

@@ -0,0 +1,6 @@
+fn main() {
+    let f: fn#() = fn# () {
+        log "This is a bare function"
+    };
+    f();
+}

src/test/run-pass/fn-bare-item.rs

@@ -0,0 +1,7 @@
+fn# f() {
+    log "This is a bare function";
+}
+
+fn main() {
+    f();
+}