Changements

DefaultDependencies: Remove unnecessary use of RxJavaHelpers
 (commit: eb6ae65)

Return Observable<String> instead of ObservableValue<String> for
TextBinding
Some text bindings used <some snapshot>.toObservableList and the
subscriptions were not disposed. This way of doing things allows
disposing subscriptions when a DOM node is destroyed.
 (commit: b177874)

RxJavaHelpers: Make some methods private
 (commit: 010ca93)

gs-reactor: Use Observables to define metabindings
– Use Observable<Snapshot<Generic>> to define a forEach and
 Observable<Optional<Context>> to define a select metabinding.
– Adapt the existing applications to this change.
– Allow sorting of Snapshots.
– Dispose subscriptions to the observables used in metabindings.
 (commit: 7b48c63)

Delete unused ObservableListWrapper class copy
 (commit: 3057bed)

Refactor: getAdds/RemovesObservable() -> getAdds()/getRemovals()
 (commit: 62964fd)

gs-reactor: Use Observable<Boolean> to define TagSwitcher
 (commit: d534c26)

Do not return ObservableValues in methods in DefaultCompositeInheritance
Return Observable<Optional<T>> instead of ObservableValue<T> for 
getObservableAttribute, getObservableHolder, etc.
To return an ObservableValue, it’s necessary to use the
toObservableList() method from Snapshot, which is deprecated since it
does not allow unsubscription from the Observables subscribed to in the
method.
Emit items of type Optional<T> rather than T because Observables can’t
emit nulls.
 (commit: 08a081e)

DefaultContext: Avoid double checking before adding to set
 (commit: 9052c43)

gs-default: memoize results in computePotentialDependencies
Avoids repeated calls to isDependencyOf due to the recursion in that
method.
 (commit: 2a37a8a)

DefaultContext: Simplify computePotentialDependencies
 (commit: 6645ebf)

DefaultGeneric: Cosmetic changes
 (commit: 04c888f)

Use memoization in more places, use share() instead of
replay().refCount()
Store Snapshots and Observables so the same instance is returned by
successive calls. This (partially) prevents exponential growth of the
number of Observables subscribed to a given Observable.
share() is the appropriate operation needed, not replay().refCount()
(the observables were not actually shared previously so it did not
matter…).
 (commit: 43e98d6)

gs-default: DefaultCompositesInheritance: Fix typo
 (commit: 294ffed)

gs-default: Do not memoize getSubInstances and getSubInheritings
This breaks real-time updates because some Snapshots that should reflect 
different caches are shared.
 (commit: c0b2a0c)

Memoize getSubInheritings and getSubInstances again
Store the memoized functions in CheckedContext instead of using a static 
variable, so this time it works as intended :-)
 (commit: cf06157)

Memoize getAttributes/getHolders
 (commit: a0c0135)

remove not-to-track files
 (commit: 4294a2f)

restore .classpath files
 (commit: 2f9f24b)

clean wd
 (commit: 8565e9e)

merge
 (commit: 666cf25)

updated project-specific gitignore
 (commit: d3bbd5c)