Avoid the use of make-coroutine-generator in srfi-158

[amirouche]

With Chez Scheme, make-coroutine-generator is slow compared to the same code that does not rely on call/cc and call/1cc.

Those can be implemented without make-coroutine-generator

• gtake
• make-for-each-generator

Maybe make-unfold-generator can be implemented without make-coroutine-generator

[amirouche]

I do not see how to implement make-for-each-generator without make-coroutine-generator some for unfold.

Fixed gtake in #63

[arcfide]

I'll go ahead and close this then as mostly done. Feel free to submit a PR for make-for-each-generator if you figure it out.