Redefine PROGMEM variables for ESP8266

redefine:
PSTR
printf_P
strlen_P
PROGMEM
pgm_read_byte
pgm_read_word

RF24.cpp

@@ -32,7 +32,7 @@ void RF24::csn(bool mode)
 	// Return, CSN toggle complete
 	return;
 	
-#elif defined(ARDUINO)
+#elif defined(ARDUINO) && !defined (RF24_SPI_TRANSACTIONS)
 	// Minimum ideal SPI bus speed is 2x data rate
 	// If we assume 2Mbs data rate and 16Mhz clock, a
 	// divider of 4 is the minimum we want.

RF24_config.h

@@ -115,9 +115,17 @@
 // Progmem is Arduino-specific
 // Arduino DUE is arm and does not include avr/pgmspace
 #if defined (ARDUINO_ARCH_ESP8266)
-  #include <pgmspace.h>
-  #define PRIPSTR "%s"
+  #include <pgmspace.h>  
+  
+  typedef uint16_t prog_uint16_t;
+  #define PSTR(x) (x)
   #define printf_P printf
+  #define strlen_P strlen  
+  #define PROGMEM
+  #define pgm_read_byte(addr) (*(const unsigned char *)(addr))
+  #define pgm_read_word(p) (*(p))
+  #define PRIPSTR "%s"
+  
 #elif defined(ARDUINO) && ! defined(__arm__) && !defined (__ARDUINO_X86__)
 	#include <avr/pgmspace.h>
 	#define PRIPSTR "%S"