Add Lwt_preemptive.run_in_main_no_wait

[kit-ty-kate]

Useful if you want Lwt_preemptive.run_in_main but does not need to wait for the result of the function to finish.

[kit-ty-kate]

Side note: personally i ended up using Lwt_unix.send_notification directly instead of using this function because the extra mutex weren't needed and made it a bit too slow and unpredictable but I feel like it might still be useful for someone someday.

[raphael-proust]

Thanks for the contribution!

I have just quickly read the diff and it looks good. I will test the feature soon and then merge.

[raphael-proust]

Considering the following changes:

• naming it run_in_main_dont_wait to be consistent with dont_wait
• adding an exception handler (otherwise exceptions raised by the lambda are lost)

I'll do that soon. Unless anyone have comments/remarks/etc. on the matter?

[raphael-proust]

I implemented the two things I mention above and also rebased

[raphael-proust]

@kit-ty-kate are you ok with the new interface? Does it work for your use-case?

[kit-ty-kate]

Looks good by me.