Support exponential notation in filter values

Closes #311
Includes testcase

lib/carto/parser.js

@@ -462,7 +462,7 @@ carto.Parser = function Parser(env) {
                 dimension: function() {
                     var c = input.charCodeAt(i);
                     if ((c > 57 || c < 45) || c === 47) return;
-                    var value = $(/^(-?\d*\.?\d+)(\%|\w+)?/);
+                    var value = $(/^(-?\d*\.?\d+(?:[eE][-+]?\d+)?)(\%|\w+)?/);
                     if (value) {
                         return new tree.Dimension(value[1], value[2], memo);
                     }

test/rendering/filterexp.mml

@@ -0,0 +1,15 @@
+{
+    "srs": "+proj=merc +a=6378137 +b=6378137 +lat_ts=0.0 +lon_0=0.0 +x_0=0.0 +y_0=0.0 +k=1.0 +units=m +nadgrids=@null +wktext +no_defs +over",
+    "Stylesheet": [
+        "filterexp.mss"
+    ],
+    "Layer": [{
+        "name": "world",
+        "srs": "+proj=merc +a=6378137 +b=6378137 +lat_ts=0.0 +lon_0=0.0 +x_0=0.0 +y_0=0.0 +k=1.0 +units=m +nadgrids=@null +wktext +no_defs +over",
+        "Datasource": {
+            "file": "http://tilemill-data.s3.amazonaws.com/test_data/shape_demo.zip",
+            "type": "shape"
+        }
+    }]
+}
+

test/rendering/filterexp.mss

@@ -0,0 +1 @@
+#world [a = 1.2e3][b = 1.2e-3][c = 1.2e+3] { polygon-fill:#fff; }

test/rendering/filterexp.result

@@ -0,0 +1,21 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!DOCTYPE Map[]>
+<Map srs="+proj=merc +a=6378137 +b=6378137 +lat_ts=0.0 +lon_0=0.0 +x_0=0.0 +y_0=0.0 +k=1.0 +units=m +nadgrids=@null +wktext +no_defs +over"  maximum-extent="-20037508.34,-20037508.34,20037508.34,20037508.34">
+
+
+<Style name="world" filter-mode="first">
+  <Rule>
+    <Filter>([a] = 1200) and ([b] = 0.0012) and ([c] = 1200)</Filter>
+    <PolygonSymbolizer fill="#ffffff" />
+  </Rule>
+</Style>
+<Layer name="world"
+  srs="+proj=merc +a=6378137 +b=6378137 +lat_ts=0.0 +lon_0=0.0 +x_0=0.0 +y_0=0.0 +k=1.0 +units=m +nadgrids=@null +wktext +no_defs +over">
+    <StyleName>world</StyleName>
+    <Datasource>
+       <Parameter name="file"><![CDATA[[absolute path]]]></Parameter>
+       <Parameter name="type"><![CDATA[shape]]></Parameter>
+    </Datasource>
+  </Layer>
+
+</Map>