CPFP support (#395)

* CPFP support.

fixes #5
fixes #353
fixes #360

* Use effectiveFeePerVsize for mempool statistics.

* Renaming endpoint cpfp-info to just cpfp.

* Renaming decended to BestDescendant.

* Updating language file with new strings.

frontend/src/app/services/api.service.ts

@@ -1,6 +1,6 @@
 import { Injectable } from '@angular/core';
 import { HttpClient, HttpParams } from '@angular/common/http';
-import { OptimizedMempoolStats } from '../interfaces/node-api.interface';
+import { CpfpInfo, OptimizedMempoolStats } from '../interfaces/node-api.interface';
 import { Observable } from 'rxjs';
 import { StateService } from './state.service';
 import { WebsocketResponse } from '../interfaces/websocket.interface';
@@ -88,4 +88,8 @@ export class ApiService {
   getInitData$(): Observable<WebsocketResponse> {
     return this.httpClient.get<WebsocketResponse>(this.apiBaseUrl + this.apiBasePath + '/api/v1/init-data');
   }
+
+  getCpfpinfo$(txid: string): Observable<CpfpInfo> {
+    return this.httpClient.get<CpfpInfo>(this.apiBaseUrl + this.apiBasePath + '/api/v1/cpfp/' + txid);
+  }
 }