Adds functionality for getClusterIndex(), selectCluster() and getCluster if the 'cluster' option is enabled.
Also getSelection() returns an object containing a 'cluster' key if a cluster is selected.
Adds documentation to 'getCluster()', and updates 'getSelection()' and the 'select' event for including references when a cluster is selected
Move maxItems from getClusters to the options object
Adds clusterMaxItems documentation
Merge branch 'master' of https://github.com/igui/chap-links-library
Merge branch 'master' of https://github.com/almende/chap-links-library
Use getItem() to not repeat logic
Merge pull request #308 from igui/master

getCluster(), getClusterIndex() and getSelection() with cluster selection info