CHANGES:

CHANGE 2: BGe 27-Nov-24
    * Internal changes
        - Lanes is implemented in C++20: thread, condition_variable, mutex, string_view, variant, lambdas, templates, and more!
        - Almost all platform-specific code is gone (only a small bit for thread priority and affinity remains).
        - Decoda support inactive by default.
        - Deep userdata interface fully revamped to C++20 too.
    * Lanes API changes
        - Version is now 4.0.0
        - Lanes module:
            - shared library is now lanes_core.[so|dll] instead of lanes/core.[so|dll]
            - lanes.register() is also available as lanes_register() in the exported C API.
            - lanes.sleep() accepts a new argument "indefinitely" to block forever (until hard cancellation is received).
            - function set_debug_threadname() available inside a Lane is renamed lane_threadname(); can now both read and write the name.
            - new function lanes.finally(). Installs a function that gets called at Lanes shutdown after attempting to terminate all lanes.
            - new function lanes.collectgarbage(), to force a full GC cycle in the keeper states.
              If some lanes still run after the finalizer, Lanes with throw an exception or freeze, depending on its return value.
            - Configuration settings:
                - Boolean parameters only accept boolean values.
                - allocator provider function is called with a string hint to distinguish internal allocations, lane and keeper states.
                - demote_full_userdata removed. Use __lanesconvert instead (see below).
                - keepers_gc_threshold added. Controls when GC runs inside keepers.
                - nb_keepers changed to nb_user_keepers. limited to 100 keepers on top of the internal keeper used by the timer Linda.
                - strip_functions added. Only useful for Lua 5.3+.
                - verbose_errors removed. Use lane error_trace_level instead.
                - with_timers is false by default.
            - Non-deep full userdata are processed during module registration just like ordinary module C functions, making them valid transferable (up)values (for example: io.stdin).
        - Lanes:
            - Can no longer be "killed" by hard-stopping their thread without any resource cleanup (see lane:cancel()).
            - lanes.gen() settings:
                - stricter check of base libraries (can raise an error if it doesn't exist in the Lua flavor it's built against).
                - error_trace_level added. Replaces the global verbose_errors setting.
                - name added. Can be used to set the name early (before the lane body calls lane_threadname()).
            - New generator lanes.coro() to start a lane as a coroutine.
            - New __close metamethod that calls join().
            - lane:join()
                - Returns nil, error in case of problem.
                - Forces lane function body must return a non-nil first value on success because of the above.
            - lane:get_debug_threadname() renamed get_threadname().
        - Lindas:
            - lanes.linda()
                - Arguments can be provided in any order.
                - Accepts a callback to be invoked by __close (see below).
                - Providing "auto" as name when constructing a Linda cause Lanes to provide a name built from the source location of the construction.
                - Specifying a group to lanes.linda() is mandatory when Lanes is configured with user Keepers.
            - linda:deep() result no longer contains the raw C pointer of the Linda object.
            - linda :receive(), :send(), :get(), :set(), :limit() return nil, error in case of problem. Returned values in case of success change too.
            - linda:limit() can be used to read the value if no new limit is provided.
            - linda:restrict() can restrain the use of send/receive or set/get on any key.
            - New __close metamethod that calls any suitable handler that was provided at Linda creation.
            - linda:dump() outputs <key>.limit as 'unlimited' instead of -1 for unlimited keys.
            - linda:wake() can wake up threads waiting for a Linda without doing any I/O on it.
            - linda.status reads the cancel status of the Linda.
            - new function linda:collectgarbage() to force collection of all stale data in the associated keeper.
            - Deep userdata are an acceptable key to send data into (for example, another linda).
        - Full userdata conversion:
            - __lanesconvert added.
            - __lanesignore removed. Use __lanesconvert instead.

CHANGE 1: BGe 9-Apr-24
    * reset changelog, next entry will list API changes since last C-implementation.

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