GDScript: Remove function of continue for match statement

The keyword is confusing and rarely is used in the intended way. It is
removed now in favor of a future feature (pattern guards) to avoid
breaking compatibility later.

modules/gdscript/tests/scripts/parser/features/match.gd

@@ -3,8 +3,6 @@ func test():
 	match i:
 		"Hello":
 			print("hello")
-			# This will fall through to the default case below.
-			continue
 		"Good bye":
 			print("bye")
 		_:

modules/gdscript/tests/scripts/parser/features/match.out

@@ -1,4 +1,3 @@
 GDTEST_OK
 hello
-default
 This will match

modules/gdscript/tests/scripts/parser/features/nested_match.gd

@@ -8,11 +8,10 @@ func test():
 				1234:
 					print("2")
 					match number:
-						1234:
-							print("3")
-							continue
+						4321:
+							print("Should not be printed")
 						_:
-							print("Should also be printed")
+							print("3")
 							match number:
 								1234:
 									print("4")

modules/gdscript/tests/scripts/parser/features/nested_match.out

@@ -2,7 +2,6 @@ GDTEST_OK
 1
 2
 3
-Should also be printed
 4
 5
 6