Implement fee inclusive transactions (#657)

* Add amount_includes_fee option in TX building

* Add --amount_includes_fee CLI option

* Implement send 'max' amount

Co-authored-by: cliik <cliik@example.com>

libwallet/src/api_impl/owner.rs

@@ -508,6 +508,7 @@ where
 			&mut *w,
 			keychain_mask,
 			args.amount,
+			args.amount_includes_fee.unwrap_or(false),
 			args.minimum_confirmations,
 			args.max_outputs as usize,
 			args.num_change_outputs as usize,
@@ -543,6 +544,7 @@ where
 			&parent_key_id,
 			true,
 			use_test_rng,
+			args.amount_includes_fee.unwrap_or(false),
 		)?
 	};
 
@@ -696,6 +698,7 @@ where
 		&parent_key_id,
 		false,
 		use_test_rng,
+		false,
 	)?;
 
 	let keychain = w.keychain(keychain_mask)?;
@@ -823,6 +826,7 @@ where
 			parent_key_id.clone(),
 			false,
 			true,
+			false,
 		)?;
 
 		// Add inputs and outputs to original context

libwallet/src/api_impl/types.rs

@@ -40,6 +40,8 @@ pub struct InitTxArgs {
 	#[serde(with = "secp_ser::string_or_u64")]
 	/// The amount to send, in nanogrins. (`1 G = 1_000_000_000nG`)
 	pub amount: u64,
+	/// Does the amount include the fee, or will fees be spent in addition to the amount?
+	pub amount_includes_fee: Option<bool>,
 	#[serde(with = "secp_ser::string_or_u64")]
 	/// The minimum number of confirmations an output
 	/// should have in order to be included in the transaction.
@@ -105,6 +107,7 @@ impl Default for InitTxArgs {
 		InitTxArgs {
 			src_acct_name: None,
 			amount: 0,
+			amount_includes_fee: None,
 			minimum_confirmations: 10,
 			max_outputs: 500,
 			num_change_outputs: 1,