add watchdog support: (wdt-init timeout panic), (wdt-add), (wdt-reset)

[hemml]

Hi! I'm using ESP32 with uL in my project and I need to watchdog support. I have added 3 functions:

(wdt-init timeout panic) - init ESP32 watchdog with timeout (in seconds) and panic flag (boolean) (wdt-add) - activate a watchdog for the current task (wdt-reset) - reset watchdog state (need to be called periodically)

[technoblogy]

Thanks for the patch. I'll think about whether it should become part of the standard release.

[technoblogy]

I don't think I'll make them part of the standard versions of uLisp. One reason is that they are ESP-specific, and I try to make everything platform independent.

However, with the new extensions-file feature I've added to Release 4.4 you could put your extensions in a separate add-on file, and users who want them can just compile your extensions file in with the standard uLisp file.

Short term you could mention the availability of your extensions on the uLisp Forum. Longer term I'm thinking about how to provide a place to collect together third-party uLisp extensions.