Checkpoint while standalone

[Nicolas]

Debugging checkpoint code can be hard if it requires running under the control of the core client, so it's often useful to make it checkpoint without caring about preferences when running as standalone. For example, making it checkpoint always​ if standalone (instead of calling boinc_time_to_checkpoint), but that causes too much I/O. Other workarounds​ that devs could use reduce performance of the application both as standalone and with client (because of all the extra function calls). One way to avoid that performance hit is using function pointers. That already gets quite messy...

I suggest adding a feature inside boinc_time_to_checkpoint itself to return true every few seconds if running standalone. Maybe make it possible to disable using #ifdef, and add a #define for changing the time between checkpoints.

[Nicolas]

A really simple workaround: make it checkpoint always

[Nicolas]

Another workaround: if standalone, call a different function