Finish off srml-contract create -> instantiate renamings (#3649)

* Finish off srml-contract create -> instantiate renamings

* bumped spec_version

substrate/srml/contracts/src/wasm/mod.rs

@@ -478,7 +478,7 @@ mod tests {
 
 	const CODE_CREATE: &str = r#"
 (module
-	;; ext_create(
+	;; ext_instantiate(
 	;;     code_ptr: u32,
 	;;     code_len: u32,
 	;;     gas: u64,
@@ -487,11 +487,11 @@ mod tests {
 	;;     input_data_ptr: u32,
 	;;     input_data_len: u32,
 	;; ) -> u32
-	(import "env" "ext_create" (func $ext_create (param i32 i32 i64 i32 i32 i32 i32) (result i32)))
+	(import "env" "ext_instantiate" (func $ext_instantiate (param i32 i32 i64 i32 i32 i32 i32) (result i32)))
 	(import "env" "memory" (memory 1 1))
 	(func (export "call")
 		(drop
-			(call $ext_create
+			(call $ext_instantiate
 				(i32.const 16)   ;; Pointer to `code_hash`
 				(i32.const 32)   ;; Length of `code_hash`
 				(i64.const 0)    ;; How much gas to devote for the execution. 0 = all.

substrate/srml/contracts/src/wasm/runtime.rs

@@ -29,7 +29,7 @@ use rstd::mem;
 use codec::{Decode, Encode};
 use sr_primitives::traits::{Bounded, SaturatedConversion};
 
-/// The value returned from ext_call and ext_create contract external functions if the call or
+/// The value returned from ext_call and ext_instantiate contract external functions if the call or
 /// instantiation traps. This value is chosen as if the execution does not trap, the return value
 /// will always be an 8-bit integer, so 0x0100 is the smallest value that could not be returned.
 const TRAP_RETURN_CODE: u32 = 0x0100;
@@ -456,7 +456,7 @@ define_env!(Env, <E: Ext>,
 	// - value_len: length of the value buffer.
 	// - input_data_ptr: a pointer to a buffer to be used as input data to the initializer code.
 	// - input_data_len: length of the input data buffer.
-	ext_create(
+	ext_instantiate(
 		ctx,
 		code_hash_ptr: u32,
 		code_hash_len: u32,