Rename TransactionCompiler to Script and use it to replace the type alias

sdk/src/lib.rs

@@ -9,6 +9,7 @@ pub mod native_program;
 pub mod packet;
 pub mod pubkey;
 pub mod rpc_port;
+pub mod script;
 pub mod shortvec;
 pub mod signature;
 pub mod system_instruction;
@@ -16,7 +17,6 @@ pub mod system_program;
 pub mod system_transaction;
 pub mod timing;
 pub mod transaction;
-mod transaction_compiler;
 
 #[macro_use]
 extern crate serde_derive;