Add String(const uint8_t *, unsigned int) constructor

This allows creating a String from a uint8_t[] or uint8_t* as well,
without having to add explicit casts.

Author: matthijskooijman

api/String.h

@@ -66,6 +66,7 @@ class String
 	// be false).
 	String(const char *cstr = "");
 	String(const char *cstr, unsigned int length);
+	String(const uint8_t *cstr, unsigned int length) : String((const char*)cstr, length) {}
 	String(const String &str);
 	String(const __FlashStringHelper *str);
 	#if __cplusplus >= 201103L || defined(__GXX_EXPERIMENTAL_CXX0X__)