New stroke-linejoin style option with a VML alternative. For Leaflet#1843.

Author: palewire

src/layer/vector/Path.SVG.js

@@ -83,6 +83,9 @@ L.Path = L.Path.extend({
 			if (this.options.linecap) {
 				this._path.setAttribute('stroke-linecap', this.options.linecap);
 			}
+			if (this.options.linejoin) {
+				this._path.setAttribute('stroke-linejoin', this.options.linejoin);
+			}
 		} else {
 			this._path.setAttribute('stroke', 'none');
 		}

src/layer/vector/Path.VML.js

@@ -85,6 +85,9 @@ L.Path = L.Browser.svg || !L.Browser.vml ? L.Path : L.Path.extend({
 			if (options.linecap) {
 				stroke.endcap = options.linecap.replace('butt', 'flat');
 			}
+			if (options.linejoin) {
+				stroke.joinstyle = options.linejoin;
+			}
 
 		} else if (stroke) {
 			container.removeChild(stroke);

src/layer/vector/Path.js

@@ -19,6 +19,7 @@ L.Path = L.Class.extend({
 		color: '#0033ff',
 		dashArray: null,
 		linecap: null,
+		linejoin: null,
 		weight: 5,
 		opacity: 0.5,