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/components/tx-fee-rating/tx-fee-rating.component.ts

@@ -52,7 +52,7 @@ export class TxFeeRatingComponent implements OnInit, OnChanges, OnDestroy {
   }
 
   calculateRatings(block: Block) {
-    const feePervByte = this.tx.fee / (this.tx.weight / 4);
+    const feePervByte = this.tx.effectiveFeePerVsize || this.tx.fee / (this.tx.weight / 4);
     this.medianFeeNeeded = block.medianFee;
 
     // Block not filled