Rename AtomicCounter::get_increment to simply next

Its a counter, `next` is super clear, `get_increment` is a bit
less so.

lightning/src/ln/interactivetxs.rs

@@ -1328,7 +1328,7 @@ mod tests {
 	impl EntropySource for TestEntropySource {
 		fn get_secure_random_bytes(&self) -> [u8; 32] {
 			let mut res = [0u8; 32];
-			let increment = self.0.get_increment();
+			let increment = self.0.next();
 			for (i, byte) in res.iter_mut().enumerate() {
 				// Rotate the increment value by 'i' bits to the right, to avoid clashes
 				// when `generate_local_serial_id` does a parity flip on consecutive calls for the

lightning/src/ln/peer_handler.rs

@@ -1053,7 +1053,7 @@ impl<Descriptor: SocketDescriptor, CM: Deref, RM: Deref, OM: Deref, L: Deref, CM
 
 	fn get_ephemeral_key(&self) -> SecretKey {
 		let mut ephemeral_hash = self.ephemeral_key_midstate.clone();
-		let counter = self.peer_counter.get_increment();
+		let counter = self.peer_counter.next();
 		ephemeral_hash.input(&counter.to_le_bytes());
 		SecretKey::from_slice(&Sha256::from_engine(ephemeral_hash).to_byte_array()).expect("You broke SHA-256!")
 	}

lightning/src/sign/mod.rs

@@ -2504,7 +2504,7 @@ impl RandomBytes {
 
 impl EntropySource for RandomBytes {
 	fn get_secure_random_bytes(&self) -> [u8; 32] {
-		let index = self.index.get_increment();
+		let index = self.index.next();
 		let mut nonce = [0u8; 16];
 		nonce[..8].copy_from_slice(&index.to_be_bytes());
 		ChaCha20::get_single_block(&self.seed, &nonce)

lightning/src/util/atomic_counter.rs

@@ -21,7 +21,7 @@ impl AtomicCounter {
 			counter: Mutex::new(0),
 		}
 	}
-	pub(crate) fn get_increment(&self) -> u64 {
+	pub(crate) fn next(&self) -> u64 {
 		#[cfg(target_has_atomic = "64")] {
 			self.counter.fetch_add(1, Ordering::AcqRel)
 		}