added esp8266 to supported architectures

added addition #include file for esp8266 to resolve missing SPI_FLASH_SEC_SIZE symbol

NmraDcc.h

@@ -91,7 +91,8 @@ typedef struct
 #define CV_29_CONFIG                          29
 
 #if defined(ESP8266)
-  #define MAXCV     SPI_FLASH_SEC_SIZE
+#include <spi_flash.h>
+#define MAXCV     SPI_FLASH_SEC_SIZE
 #else
 #define MAXCV                                 E2END     // the upper limit of the CV value currently defined to max memory.
 #endif

library.properties

@@ -6,4 +6,4 @@ sentence=Enables NMRA DCC Communication
 paragraph=This library allows you to interface to a NMRA DCC track signal and receive DCC commands. The library currently supports the AVR ATTiny84/85 & ATMega88/168/328/32u4 and Teensy 3.x using the INT0/1 Hardware Interrupt and micros() ONLY and no longer uses Timer0 Compare Match B, which makes it much more portable to other platforms
 category=Communication
 url=http://mrrwa.org/dcc-decoder-interface/
-architectures=avr
+architectures=avr,esp8266