PgmSpace working

PSTR() and F() macros correctly place string into flash memory relying
on PROGMEM
PROGMEM uses ICACHE_RODATA_ATTR
Print and String classes fixed up
str* classes fixed up

cores/esp8266/Print.h

@@ -63,6 +63,7 @@ class Print {
             return write((const uint8_t *) buffer, size);
         }
 
+        size_t print(const __FlashStringHelper *);
         size_t print(const String &);
         size_t print(const char[]);
         size_t print(char);
@@ -74,6 +75,7 @@ class Print {
         size_t print(double, int = 2);
         size_t print(const Printable&);
 
+        size_t println(const __FlashStringHelper *);
         size_t println(const String &s);
         size_t println(const char[]);
         size_t println(char);