ol.layer.Vector.getSource return type specialisation.
Remove unnecessary type cast
snapshot
Revert "snapshot"

This reverts commit 47fd7d86266bce0e269788aff556df8c09879165.
Merge pull request #2669 from fredj/bad-commit

Revert "snapshot"
Merge pull request #2651 from gberaudo/layer_vector_source_specialisation

ol.layer.Vector.getSource return type specialisation.
Add olx.layer.ImageOptions typedef
Set ol.layer.Image#getSource return type to ol.source.Image
Remove unnecessary type cast
Set ol.layer.Tile#getSource return type to ol.source.Tile
Remove unnecessary type cast
Merge pull request #2656 from fredj/image-layer-source-type

Set ol.layer.Image#getSource return type to ol.source.Image
Remove unnecessary newlines
Remove unnecessary parentheses