Add getBounds, fitBounds, Rectangle

[jczerosb]

getBounds, fitbounds and Rectangle are existing features in Leaflet, getBounds is used to get a rectangular area used by Circle, Rectangle, Polygon, Polylines, etc. fitBounds is used to Zoom an specific area, usually enclosed by getBounds result. Rectangle, can be created just with SW/NE coords, no need a Polyline with 4 corners.

For getBounds result a new class should be created to collect results in SW/NE format, also same class have a extension method for fitBounds

[jim-craane]

Is this still going to be merged? I need this features for my project.