Say "IR" instead of "IL".

While the specifics of these terms are debatable, "IR" generally
isn't incorrect in this context, and is the more widely recognized
term at this time.

See also the discussion in #267.

Fixes #267.

lib/wasm/src/module_translator.rs

@@ -10,7 +10,7 @@ use environ::ModuleEnvironment;
 
 use std::string::String;
 
-/// Translate a sequence of bytes forming a valid Wasm binary into a list of valid Cretonne IL
+/// Translate a sequence of bytes forming a valid Wasm binary into a list of valid Cretonne IR
 /// [`Function`](../cretonne/ir/function/struct.Function.html).
 /// Returns the functions and also the mappings for imported functions and signature between the
 /// indexes in the wasm module and the indexes inside each functions.