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

jerry-core/jerry.c

@@ -30,7 +30,7 @@
 #include "ecma-objects.h"
 #include "ecma-objects-general.h"
 #include "jcontext.h"
-#include "jerry-api.h"
+#include "jerryscript.h"
 #include "jerry-debugger.h"
 #include "js-parser.h"
 #include "re-compiler.h"