Added repl and some documentation. Improved error messages. Removed dead code.

* Removed same_variant in parse::parsetree
* Added SExp::multistep (for use of the repl)

Improved error messages:
* Added parenthesis around types
* Changed how errors propagate inferring generics:
  added the error variant ArgumentsDontMatchGeneric,
  implemented the displaying of it, added tests for
  it.
* Had to change some tests to match for the new changes

1 files changed, 8 insertions, 0 deletions

diff --git a/src/sexp/step.rs b/src/sexp/step.rs
index 765e33c..1ab0291 100644
--- a/src/sexp/step.rs
+++ b/src/sexp/step.rs
@@ -209,4 +209,12 @@ impl SExp {
             t => Err(format!("unimplemented: {:?}.step()", t)),
         }
     }
+
+
+    pub fn multistep(self) -> Result<Self, String> {
+        match self.clone().step()? {
+            x if x == self => Ok(self),
+            x => x.multistep()
+        }
+    }
 }