Merge instance into context (#2501)

There was quite some confusion about terminology around instances
and contexts. All the docs mentioned external contexts but
functions and types were referring to instances, and the relation
between these two concepts were not clear. This commit keeps
(external) context as the only surviving concept.

JerryScript-DCO-1.0-Signed-off-by: Akos Kiss akiss@inf.u-szeged.hu

jerry-core/include/jerryscript-core.h

@@ -281,9 +281,9 @@ typedef struct
 } jerry_context_data_manager_t;
 
 /**
- * Function type for allocating buffer for JerryScript instance.
+ * Function type for allocating buffer for JerryScript context.
  */
-typedef void *(*jerry_instance_alloc_t) (size_t size, void *cb_data_p);
+typedef void *(*jerry_context_alloc_t) (size_t size, void *cb_data_p);
 
 /**
  * Type information of a native pointer.
@@ -294,9 +294,9 @@ typedef struct
 } jerry_object_native_info_t;
 
 /**
- * An opaque declaration of the JerryScript instance structure.
+ * An opaque declaration of the JerryScript context structure.
  */
-typedef struct jerry_instance_t jerry_instance_t;
+typedef struct jerry_context_t jerry_context_t;
 
 /**
  * General engine functions.
@@ -517,7 +517,7 @@ bool jerry_is_valid_cesu8_string (const jerry_char_t *cesu8_buf_p, jerry_size_t
 /*
  * External context functions.
  */
-jerry_instance_t *jerry_create_instance (uint32_t heap_size, jerry_instance_alloc_t alloc, void *cb_data_p);
+jerry_context_t *jerry_create_context (uint32_t heap_size, jerry_context_alloc_t alloc, void *cb_data_p);
 
 /**
  * Miscellaneous functions.