StreamingRenderer should answer GetFeatureInfo like queries
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                 Key: GEOT-1218
                 URL: http://jira.codehaus.org/browse/GEOT-1218
             Project: GeoTools
          Issue Type: Improvement
          Components: core render
    Affects Versions: 2.3.0, 2.4.M0
            Reporter: Andrea Aime
         Assigned To: Jesse Eichar
             Fix For: 2.4.M1


The renderer itself is the only compontent that can answer a GetFeatureInfo 
request properly 100% of the times, independent of how complex and fancy the 
styling is.
A getFeatures method would return a feature collection of features that are 
drawn in a certain area around a central pixel (hit area), using pixel based 
techniques to solve the query.
In particular.
* for raster features, and for vector features and non text symbolizers, render 
just the hit area + meta buffer, and say a Feature is catched only when it 
stains the hit area during its rendering. Should not be that complex, have a 
refererence to the feature, setup a transparent buffered image, render, check 
if any pixel turned to non trasparent, if so, add the feature to the resutls
* for labels, the same, but you have to render the whole map area to make sure 
we don't alter label positions.

If the catch area is big this method may become quite slow, but it's the only 
one that guarantees 100% hit accuracy. Alternative methods may use vector 
oriented techniques, but having attribute dependend symbolizers would make them 
extremely difficult to implement properly.

Jesse, I've assigned this one to you so that you can have a look at it, but I 
guess I'll end up implementing this one myself if you agree.

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