WIP: Trying to fix suspend while scheduler running

WIP: You were right, root doesn’t need a stack

WIP: Fix creating root fiber

WIP: Fix root stack

WIP: Suspend main

WIP: Suspend main

Fix true / false → 1 / 0

Put Future definition in fiber.c

Return Scheduler from Future::schedule()

Add Future interface

Use callback given to suspend to resume fiber

Switch Fiber::create() to Fiber::run()

Split getStatus() method

Split into isSuspended(), isRunning(), and isTerminated().

Better handling of private constructors

Use static constructor for Fiber

Simplify API

Copy return only if used

Fix spaces vs. tabs

Add Fiber::getCurrent()

Fix occasional segfault with finally

Swap license

The code originally was released under the PHP license.

Add FiberError

FiberError is thrown on user errors, such as suspending outside a fiber.

Use ini entry for stack size

Add ucontext support

Update stub with PHP 8 mixed type