- Also refactored internals to use weak/shared pointers

This allows real-time threads to join an audio workgroup on Apple platforms.

- added unit tests
- best performance timers used for each platform
- fixed an issue in which timer callbacks could drift

This commit adds the JUCE_DECLARE_SCOPED_ENUM_BITWISE_OPERATORS macro, enabling bitwise operators on scoped enums. This feature simplifies the use of scoped enums in situations where bitwise operations are needed.

This is a breaking change - see BREAKING-CHANGES.txt

This patch also makes Optional public to end users.

Please see the forum post "Re-structuring of JUCE’s low-level Android code" and the BREAKING-CHANGES.txt for more information.