Using F macro in String processor

[Daryavahus]

My project uses more RAM, so I decided to reduce amount of RAM using by AsyncWebserver. I changed in String void to code: (var == F("SOMECHAR")){return(...);} I can see now, that var characters use less memory than without F macro. My website uses over 200 var characters and I reduced RAM occupie from 23KB to over 30KB. It's a lot of memory. My ESP became more stable. ESP errors were eliminated.

[DRSDavidSoft]

This is actually one of the great optimizations done in the mathieucarbou's fork: https://github.com/mathieucarbou/ESPAsyncWebServer/

All strings are in PROGMEM in the fork, as far as I can see.