Add type conversion traits in case no_std is enabled

Author: jakelang

src/convert.rs

@@ -0,0 +1,9 @@
+use super::*;
+
+pub trait From<T>: Sized {
+    fn from(_: T) -> Self;
+}
+
+pub trait Into<T>: Sized {
+    fn from(self) -> T;
+}

src/lib.rs

@@ -1,3 +1,5 @@
+#[cfg(not(feature = "std"))]
+pub mod convert;
 /// ewasm_api is a library used to interface with Ethereum's EEI in Ewasm, a set of enhancements to
 /// the Ethereum smart contract platform.
 /// ewasm_api exposes both a set of unsafe "native" functions representing the actual EEI
@@ -18,7 +20,6 @@
 ///     finish_data(&a.bytes);
 /// }
 /// ```
-
 pub mod types;
 
 mod native;