Fix calculate start date of tasks (#17)

* Fix calculate start date of tasks
* Remove breakpoints
* Add changelog, up version to 1.0.1

Author: MrMeison

CHANGELOG.md

@@ -0,0 +1,2 @@
+## 1.0.1
+* Fixed start date calculation

package.json

@@ -1,6 +1,6 @@
 {
   "name": "powerbi-visuals-gantt",
-  "version": "0.5.2",
+  "version": "1.0.1",
   "description": "A Gantt chart is a type of bar chart which illustrates a project timeline or schedule. The Gantt Chart visual shows the Tasks, Start Dates, Durations, % Complete, and Resources for a project. The Gantt Chart visual can be used to show current schedule status using percent-complete shadings and a vertical \"TODAY\" line. The Legend may be used to group or filter tasks based upon data values.",
   "repository": {
     "type": "git",

pbiviz.json

@@ -4,7 +4,7 @@
     "displayName": "Gantt",
     "guid": "Gantt1448688115699",
     "visualClassName": "Gantt",
-    "version": "0.5.2",
+    "version": "1.0.1",
     "description": "A Gantt chart is a type of bar chart which illustrates a project timeline or schedule. The Gantt Chart visual shows the Tasks, Start Dates, Durations, % Complete, and Resources for a project. The Gantt Chart visual can be used to show current schedule status using percent-complete shadings and a vertical \"TODAY\" line. The Legend may be used to group or filter tasks based upon data values.",
     "supportUrl": "http://community.powerbi.com",
     "gitHubUrl": "https://github.com/Microsoft/powerbi-visuals-gantt"

src/gantt.ts

@@ -738,7 +738,7 @@ module powerbi.extensibility.visual {
             if (tasks.length < Gantt.MinTasks) {
                 return;
             }
-            let startDate: Date = tasks[0].start;
+            let startDate: Date = _.minBy(tasks, (t) => t.start).start;
             let endDate: Date = _.maxBy(tasks, (t) => t.end).end;
             let dateTypeMilliseconds: number = Gantt.getDateType(this.viewModel.settings.dateType.type);
             let ticks: number = Math.ceil(Math.round(endDate.valueOf() - startDate.valueOf()) / dateTypeMilliseconds);