Add linker flag ICACHE_RAM_ATTR in ISR to support ESP8266 controllers

[roku133]

ISR in ESP8266 based controllers have to be located in RAM area to avoid crashes during execution.
Therefore, I propose to conditionally add the flag ICACHE_RAM_ATTR in the source code.

My addition in RFControl.cpp
287c287
< void ICACHE_RAM_ATTR handleInterrupt() {

void handleInterrupt() {
fixed the issue.

[roku133]

sorry concerning the formatting problem in my comment above ...