Add more content for the API doc

Involves additions to (there will be subsequent pull requests for other
classes):
- ol.Attribution
- ol.Collection
- ol.Expression
- ol.Feature
- ol.Geolocation
- ol.Map
- ol.Object
- ol.Overlay
- ol.Projection
- ol.View2D
- ol.control.Attribution
- ol.control.Control
- ol.control.FullScreen
- ol.control.Logo
- ol.control.MousePosition
- ol.control.ScaleLine
- ol.control.Zoom
- ol.control.ZoomSlider
- ol.dom.Input
- ol.filter.Filter
- ol.filter.Geometry
- ol.filter.Logical
address review comments
Merge pull request #783 from bartvde/apidoc2

Add more content for the API doc (r=@twpayne,@tschaub,@fredj)
Replace tileUrl with tileURL
Replace imageUrl with imageURL
Replace Url with URL in jsdoc
Replace baseUrl with baseURL
Replace url with URL in comments
Replace expandUrl with expandURL
Replace getUrl with getURL
Clean up whitespace