replaced IconDataProvider with ClusterOptionsProvider
modified DemoIconProvider to implement ClusterOptionsProvider
cluster groups demo using getClusterGroup
updated version to 1.5, demo version 1.2
Merge branch 'release/1.5_cluster_groups' into develop
set API key for demo, not to worry about it again
added README.md
removed unused import
sonar: Avoid throwing null pointer exceptions.
simplified boolean expression
sonar: Avoid throwing null pointer exceptions.
private constructor for util
missing curly braces
util classes final
demagicified numbers
- merge of source develop branch