fixup first month and improve test

Author: archmoj

src/plots/cartesian/align_period.js

@@ -40,7 +40,7 @@ module.exports = function alignPeriod(trace, ax, axLetter, vals) {
                 var dateStr = ms2DateTime(vals[i], 0, ax.calendar);
                 var d = new Date(dateStr);
                 var year = d.getFullYear();
-                var month = d.getMonth();
+                var month = d.getMonth() + 1;
 
                 var totalDaysInMonths = 0;
                 for(var k = 0; k < period; k++) {

test/image/baselines/period_positioning3.png

@@ -10,6 +10,17 @@
             "x": ["2001-01-01", "2001-02-01", "2001-03-01", "2001-04-01"],
             "xperiodalignment": "middle"
         },
+        {
+            "xaxis": "x",
+            "yaxis": "y",
+            "xperiod": "M1",
+            "name": "scatter (M1)",
+            "type": "scatter",
+            "y": [1, 2, 3, 4],
+            "x": ["2001-01-01", "2001-02-01", "2001-03-01", "2001-04-01"],
+            "xperiodalignment": "end"
+        },
+
         {
             "xaxis": "x2",
             "yaxis": "y2",
@@ -20,6 +31,16 @@
             "x": ["2001-01-01", "2001-03-01", "2001-05-01", "2001-07-01"],
             "xperiodalignment": "middle"
         },
+        {
+            "xaxis": "x2",
+            "yaxis": "y2",
+            "xperiod": "M2",
+            "name": "scatter (M2)",
+            "type": "scatter",
+            "y": [1, 2, 3, 4],
+            "x": ["2001-01-01", "2001-03-01", "2001-05-01", "2001-07-01"],
+            "xperiodalignment": "end"
+        },
 
         {
             "xaxis": "x3",
@@ -31,6 +52,17 @@
             "x": ["2001-01-01", "2001-04-01", "2001-07-01", "2001-10-01"],
             "xperiodalignment": "middle"
         },
+        {
+            "xaxis": "x3",
+            "yaxis": "y3",
+            "xperiod": "M3",
+            "name": "scatter (M3)",
+            "type": "scatter",
+            "y": [1, 2, 3, 4],
+            "x": ["2001-01-01", "2001-04-01", "2001-07-01", "2001-10-01"],
+            "xperiodalignment": "end"
+        },
+
         {
             "xaxis": "x4",
             "yaxis": "y4",
@@ -41,6 +73,17 @@
             "x": ["2001-01-01", "2001-07-01", "2002-01-01", "2002-07-01"],
             "xperiodalignment": "middle"
         },
+        {
+            "xaxis": "x4",
+            "yaxis": "y4",
+            "xperiod": "M6",
+            "name": "scatter (M6)",
+            "type": "scatter",
+            "y": [1, 2, 3, 4],
+            "x": ["2001-01-01", "2001-07-01", "2002-01-01", "2002-07-01"],
+            "xperiodalignment": "end"
+        },
+
         {
             "xaxis": "x5",
             "yaxis": "y5",
@@ -51,6 +94,17 @@
             "x": ["2001-01-01", "2002-01-01", "2003-01-01", "2004-01-01"],
             "xperiodalignment": "middle"
         },
+        {
+            "xaxis": "x5",
+            "yaxis": "y5",
+            "xperiod": "M12",
+            "name": "scatter (M12)",
+            "type": "scatter",
+            "y": [1, 2, 3, 4],
+            "x": ["2001-01-01", "2002-01-01", "2003-01-01", "2004-01-01"],
+            "xperiodalignment": "end"
+        },
+
         {
             "xaxis": "x6",
             "yaxis": "y6",
@@ -60,6 +114,16 @@
             "y": [1, 2, 3, 4],
             "x": ["2001-01-01", "2002-01-01", "2003-01-01", "2004-01-01"],
             "xperiodalignment": "middle"
+        },
+        {
+            "xaxis": "x6",
+            "yaxis": "y6",
+            "xperiod": 31557600000,
+            "name": "scatter (AVG-YEAR)",
+            "type": "scatter",
+            "y": [1, 2, 3, 4],
+            "x": ["2001-01-01", "2002-01-01", "2003-01-01", "2004-01-01"],
+            "xperiodalignment": "end"
         }
     ],
     "layout": {