FE tool - enable FeatureGrid pluging for trace layer

[Ben Wyss]

As bug 877167 can not be build at the moment, a workaround is to allow the user to select multiple traces from the grid using FeatureGrid.
Documentation: http://opengeo.github.com/gxp/lib/plugins/FeatureGrid.html

Example:
http://gxp.opengeo.org/master/examples/featuregrid.html
http://gxp.opengeo.org/master/examples/featuregrid.js

also please be aware of this resource: http://workshops.opengeo.org/gxp/

[Ben Wyss (bmwyss)]

To allow for the user to select multiple features from a grid, this project is using 'xtype grid' https://github.com/AIFDR/tsudat2-client/blob/master/app/static/script/app/TsuDat2/Scenario.js

[Anton Gritsay (angri)]

This patch allows traces to be selected by clicking on on the map (not only in the grid).

[Anton Gritsay (angri)]

The following change to gxp code allows to enable multiselect in a grid:

diff --git a/src/script/plugins/FeatureGrid.js b/src/script/plugins/FeatureGrid.js
index 4f7478a..7ed23be 100644
--- a/src/script/plugins/FeatureGrid.js
+++ b/src/script/plugins/FeatureGrid.js
@@ -145,6 +145,7 @@ gxp.plugins.FeatureGrid = Ext.extend(gxp.plugins.ClickableFeatures, {
         // a minimal SelectFeature control - used just to provide select and
         // unselect, won't be added to the map unless selectOnMap is true
         this.selectControl = new OpenLayers.Control.SelectFeature(featureManager.featureLayer);
+ this.selectControl.multiple = true;
         if (this.selectOnMap) {
              if (featureManager.paging) {
                 this.selectControl.events.on({

Somehow we need to add some hook to FeatureGrid.addOutput() call or shortly after it. Listening to "activate" event doesn't help because it is called before addOutput().