Add jerryscript.h and mark jerry-api.h as deprecated (#1579)

Add a notification for JerryScript API users that the jerry-api.h
will be removed in the future and should use the jerryscript.h
header instead.

Also update the examples in the docs and the targets where
the jerry-api.h is used.

JerryScript-DCO-1.0-Signed-off-by: Peter Gal pgal.u-szeged@partner.samsung.com

targets/zephyr/src/main-zephyr.c

@@ -21,7 +21,7 @@
 #include <misc/printk.h>
 #include "getline-zephyr.h"
 
-#include "jerry-api.h"
+#include "jerryscript.h"
 
 static jerry_value_t print_function;