Removing jerryscript.h include from jrt.h

[zherczeg]

It was a shock for me to realize that the public API is available everywhere in the project because it is inluded in jrt.h. JerryScript has an opposite design: we have public/internal aliases for many types. E.g. jerry_value_t (public) is the same as ecma_value_t (private), jerry_length_t (public) = ecma_length_t (private), etc.

However, I realized that now certain types are crawling into the internal side from the public side. This dependency should be dropped. I am willing to work on this.

[akosthekiss]

I was the one who opposed against something similar in the referenced PR, so I should speak, I guess: OK with me if done consistently.

[akosthekiss]

While I've been looking at various parts of the code, I found some of the mentioned public types without private counterpart used internally:

• jerry-core/ecma: jerry_object_free_callback_t, jerry_object_native_info_t, jerry_external_handler_t
• jerry-core/jcontext: jerry_vm_exec_stop_callback_t

Hope it helps.

BTW, I've run into two strangely named public types: jerry_user_context_init_cb, jerry_user_context_deinit_cb (they have _cb suffix instead of the common _t). It's certainly not nice to use multiple naming schemes in the public API. So, if you're already working on the public/private type aliases, I'd suggest to rename these outlier public types, too.