Rename libraries

libctonfile -> libreader.

This library will only provide .cton file reading/parsing services which are
not needed after deployment.

Code for writing .cton files lives in the main cretonne library because it is
fairly small, and because it is useful for extracting test cases from a
deployed library.

src/libreader/lib.rs

@@ -0,0 +1,16 @@
+
+// ====------------------------------------------------------------------------------------==== //
+//
+// Cretonne file reader library.
+//
+// ====------------------------------------------------------------------------------------==== //
+//
+// The cton_reader library supports reading and writing .cton files. This functionality is needed
+// for testing Cretonne, but is not essential for a JIT compiler.
+//
+// ====------------------------------------------------------------------------------------==== //
+
+extern crate cretonne;
+
+pub mod lexer;
+pub mod parser;