Merge pull request #163 from UrbanCompass/tim/threadsafe_disposal

Threadsafe subscriber mutations and dispose on deinit

Dispose on deinit

Use NSRecursiveLock for subscriber reads/writes

Dispose on deinit

Use NSRecursiveLock for subscriber reads/writes

Merge pull request #161 from UrbanCompass/tim/revert

Revert "Dispose on deinit"

Merge pull request #158 from UrbanCompass/tim/add_variable_map

Re-add Variable map

Merge pull request #158 from UrbanCompass/tim/add_variable_map

Re-add Variable map

Merge pull request #154 from UrbanCompass/tc/disposer-fix

Dispose on deinit

Merge pull request #155 from UrbanCompass/add-zip-operator

Add zip operator

Merge pull request #153 from UrbanCompass/luis/update-combine-latest

Fix combineLatest to only finish when all are done

Merge pull request #149 from UrbanCompass/luis/snail-take

Add take(first:) operator to Observable