Merge pull request #996 from plotly/maxpt_dflt

add streaming maxpoints max and dflt

Author: cldougl

src/plots/attributes.js

@@ -94,6 +94,8 @@ module.exports = {
         maxpoints: {
             valType: 'number',
             min: 0,
+            max: 10000,
+            dflt: 500,
             role: 'info',
             description: [
                 'Sets the maximum number of points to keep on the plots from an',