Basic support for esp8266 platform

This includes empty stubs for most core Arduino functions.
Need to actually implement all those digital reads writes whatever.
Need to prebuild toolchains (xtensa-elf-lx106) for 3 platforms and put them on some download server.
Need to do the same with esptool.
Need to fix 0x40000 binary generation and add correct upload commands.
Maybe even implement uploads over WiFi.

cores/esp8266/stdlib_noniso.h

@@ -0,0 +1,26 @@
+#ifndef STDLIB_NONISO_H
+#define STDLIB_NONISO_H
+
+#ifdef __cplusplus
+extern "C"{
+#endif
+
+
+char* itoa (int val, char *s, int radix);
+
+char* ltoa (long val, char *s, int radix);
+
+char* utoa (unsigned int val, char *s, int radix);
+
+char* ultoa (unsigned long val, char *s, int radix);
+
+char* dtostre (double val, char *s, unsigned char prec, unsigned char flags);
+ 
+char* dtostrf (double val, signed char width, unsigned char prec, char *s);
+
+#ifdef __cplusplus
+} // extern "C"
+#endif
+
+
+#endif