feat: microstructure price-impact & depth indicators (part 3 of 4) (#122)

* feat: effective spread microstructure indicator (part 3 of 4)

* feat: realized spread microstructure indicator (part 3 of 4)

* feat: kyle's lambda microstructure indicator (part 3 of 4)

* feat: depth slope microstructure indicator (part 3 of 4)

bindings/node/index.d.ts

@@ -2232,6 +2232,15 @@ export declare class QuotedSpread {
   isReady(): boolean
   warmupPeriod(): number
 }
+export type DepthSlopeNode = DepthSlope
+export declare class DepthSlope {
+  constructor()
+  update(bidPx: Array<number>, bidSz: Array<number>, askPx: Array<number>, askSz: Array<number>): number | null
+  batch(snapshots: Array<ObSnapshot>): Array<number>
+  reset(): void
+  isReady(): boolean
+  warmupPeriod(): number
+}
 export type OrderBookImbalanceTopNNode = OrderBookImbalanceTopN
 export declare class OrderBookImbalanceTopN {
   constructor(levels: number)
@@ -2268,6 +2277,33 @@ export declare class TradeImbalance {
   isReady(): boolean
   warmupPeriod(): number
 }
+export type EffectiveSpreadNode = EffectiveSpread
+export declare class EffectiveSpread {
+  constructor()
+  update(price: number, size: number, isBuy: boolean, mid: number): number | null
+  batch(price: Array<number>, size: Array<number>, isBuy: Array<boolean>, mid: Array<number>): Array<number>
+  reset(): void
+  isReady(): boolean
+  warmupPeriod(): number
+}
+export type RealizedSpreadNode = RealizedSpread
+export declare class RealizedSpread {
+  constructor(horizon: number)
+  update(price: number, size: number, isBuy: boolean, mid: number): number | null
+  batch(price: Array<number>, size: Array<number>, isBuy: Array<boolean>, mid: Array<number>): Array<number>
+  reset(): void
+  isReady(): boolean
+  warmupPeriod(): number
+}
+export type KylesLambdaNode = KylesLambda
+export declare class KylesLambda {
+  constructor(window: number)
+  update(price: number, size: number, isBuy: boolean, mid: number): number | null
+  batch(price: Array<number>, size: Array<number>, isBuy: Array<boolean>, mid: Array<number>): Array<number>
+  reset(): void
+  isReady(): boolean
+  warmupPeriod(): number
+}
 export type SharpeRatioNode = SharpeRatio
 export declare class SharpeRatio {
   constructor(period: number, riskFree: number)