Remove unsupported line chart point style.

Doesn't seem like triangular point styles are currently supported, so,
this commit removes cruft.

@@ -337,15 +337,6 @@
 
                 last_x = x;
                 last_y = y;
-            }
-            // Triangular point
-            else if (chartData.inflexionPointStyle == PNLineChartPointStyleTriangle) {
-
-                if ( i != 0 ) {
-                    [progressline addLineToPoint:CGPointMake(x, y)];
-                }
-
-                [progressline moveToPoint:CGPointMake(x, y)];
             } else {
 
                 if ( i != 0 ) {

@@ -5,15 +5,11 @@
 
 #import <Foundation/Foundation.h>
 
-/**
- *  not support PNLineChartPointStyleTriangle style recently
- */
 typedef NS_ENUM(NSUInteger, PNLineChartPointStyle) {
     
     PNLineChartPointStyleNone = 0,
-    PNLineChartPointStyleCircle,
-    PNLineChartPointStyleTriangle,
-    PNLineChartPointStyleSquare
+    PNLineChartPointStyleCircle = 1,
+    PNLineChartPointStyleSquare = 3
 };
 
 @class PNLineChartDataItem;