Panicf is excessive

[c-smile]

Here:

go-sciter/sciter.go

Line 1518 in 99cd4de

log.Panicf("Unhandled sciter event case: 0x%04X.\nCheck `EVENT_GROUPS` in sciter-x-behavior.h in the latest Sciter SDK", evtg)

Panicf is excessive - not future compatible.

Please see: https://sciter.com/forums/topic/build-success-on-mac-os-but-run-error/ for the details.