some refactoring

hopefully improved rendering speed
added support to add .obj obstacles

res/icons/objects.svg

@@ -0,0 +1,51 @@
+<?xml version="1.0" encoding="iso-8859-1"?>
+<!-- Generator: Adobe Illustrator 16.0.0, SVG Export Plug-In . SVG Version: 6.00 Build 0)  -->
+<!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN" "http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd">
+<svg version="1.1" id="Capa_1" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" x="0px" y="0px"
+	 width="49.16px" height="49.16px" viewBox="0 0 49.16 49.16" style="enable-background:new 0 0 49.16 49.16;" xml:space="preserve"
+	>
+<g>
+	<g>
+		<g>
+			<path d="M43.58,22.577c-4.411,0-8,3.589-8,8v1.461c-1.771-0.633-5.197-1.461-11-1.461c-5.803,0-9.228,0.828-11,1.461v-1.461
+				c0-4.411-3.589-8-8-8c-2.757,0-5,2.243-5,5c0,2.023,1.208,3.838,3.079,4.617c0.56,0.234,0.921,0.777,0.921,1.383l1,4
+				c0,3.59,2.719,6.555,6.206,6.952c-0.821,0.392-1.393,1.224-1.393,2.192c0,1.348,1.092,2.438,2.438,2.438s2.438-1.092,2.438-2.438
+				c0-0.934-0.532-1.734-1.304-2.146h21.233c-0.772,0.409-1.304,1.211-1.304,2.146c0,1.348,1.092,2.438,2.438,2.438
+				s2.438-1.092,2.438-2.438c0-0.97-0.571-1.802-1.394-2.192c3.484-0.397,6.203-3.362,6.203-6.952l1-4
+				c0-0.606,0.361-1.147,0.921-1.383c1.871-0.778,3.079-2.594,3.079-4.617C48.58,24.82,46.337,22.577,43.58,22.577z"/>
+			<path d="M16.33,28.239c2.081-0.38,4.79-0.662,8.25-0.662s6.169,0.282,8.25,0.662c0.786-3.62,3.363-6.574,6.751-7.901V15
+				c0-8.284-6.716-15-15.001-15c-8.284,0-15,6.716-15,15v5.339C12.967,21.666,15.544,24.62,16.33,28.239z"/>
+		</g>
+	</g>
+</g>
+<g>
+</g>
+<g>
+</g>
+<g>
+</g>
+<g>
+</g>
+<g>
+</g>
+<g>
+</g>
+<g>
+</g>
+<g>
+</g>
+<g>
+</g>
+<g>
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+<g>
+</g>
+<g>
+</g>
+<g>
+</g>
+<g>
+</g>
+<g>
+</g>
+</svg>