added lrem convenience method

Sources/Redis/Client/Commands/Redis+List.swift

@@ -65,6 +65,19 @@ extension RedisClient {
         return command("LPOP", [RedisData(bulk: list)])
     }
 
+    /// Removes the first count occurrences of elements equal to value from the list
+    /// stored at key.
+    ///
+    /// https://redis.io/commands/LREM
+    public func lrem(_ list: String, count: Int, value: RedisData) -> Future<Int> {
+        return command("LREM", [RedisData(bulk: list), RedisData(bulk: String(count)), value]).map(to: Int.self) { data in
+            guard let value = data.int else {
+                throw RedisError(identifier: "lrem", reason: "Could not convert resp to int.")
+            }
+            return value
+        }
+    }
+
     /// Atomically returns and removes the last element (tail) of the list stored at source,
     /// and pushes the element at the first element (head) of the list stored at destination.
     public func rpoplpush(source: String, destination: String) -> Future<RedisData> {

Tests/RedisTests/RedisTests.swift

@@ -252,6 +252,12 @@ class RedisTests: XCTestCase {
         let brpoplpushResp3 = try redis.lpop("list2").wait()
         XCTAssertEqual(brpoplpushResp3.string, "hello")
 
+        let _ = try redis.lpush([RedisData(bulk: "hello"), RedisData(bulk: "hello1"), RedisData(bulk: "hello")], into: "mylist").wait()
+
+        XCTAssertEqual(try redis.length(of: "mylist").wait(), 3)
+        XCTAssertEqual(try redis.lrem("mylist", count: 1, value: "hello").wait(), 1)
+        XCTAssertEqual(try redis.length(of: "mylist").wait(), 2)
+
         _ = try redis.delete(["mylist", "list2"]).wait()
     }