How to extend Loki's OpenAL
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Loki's OpenAL implementation include some functions which are
specific to the implementation. These functions all have the suffix
`_LOKI' to distinguish them.
In order to use these extensions, the application will need to query
their existence via `IsExtensionPresent', and then use `GetProcAddress'
to resolve the address of the extension. The result of
`GetProcAddress' will need to be cast to the appropriate function type.