add interval splitting for bar charts

pdb-js/src/app/visualization-page/visualization-page.component.html

@@ -32,6 +32,19 @@
       
       <pdb-limit-by #limitbycomponent></pdb-limit-by>
       
+      <mat-form-field>
+        <mat-label>Intervals:</mat-label>
+        <mat-select [(value)]="intervalUnit">
+          <mat-option value="NO_INTERVAL">-</mat-option>
+          <mat-option value="MINUTE">minute</mat-option>
+          <mat-option value="HOUR">hour</mat-option>
+          <mat-option value="DAY">day</mat-option>
+          <mat-option value="WEEK">week</mat-option>
+          <mat-option value="MONTH">month</mat-option>
+          <mat-option value="YEAR">year</mat-option>
+        </mat-select>
+      </mat-form-field>
+      
      <pdb-y-axis-definition #y1AxisDefinitionComponent yIndex="1"></pdb-y-axis-definition>
      <pdb-y-axis-definition #y2AxisDefinitionComponent yIndex="2" *ngIf="y2AxisAvailable"></pdb-y-axis-definition>