Memory optimization: Do not retain LinkedHashSets in caches

LinkedHashSets are replaced with tight ArrayLists
Memory optimization: Fewer ConcurrentHashMap.Segment instances
Merge stored empty lists and sets to singe object
Memory optimization. Do not put sets into caches
Fixed accidental override of new method in IDEA API.
Converting JetScope's implementations to Kotlin (in progress)
Converted method to property
Converted to Kotlin
Converted to Kotlin
Minor code simplifications using Kotlin
Converted WritableScope to Kotlin
Converted ChainedScope to Kotlin
Converted FilteringScope to Kotlin
Converted SubstitutingScope to Kotlin
Simplified code
Converted LazyImportScopy to Kotlin
Minor code simplifications
Converted 2 more JetScope implementations to Kotlin
Workaround for compiler's bug
Trying to workaround compiler's bug