Reorganize tests and benchmark scripts.

Mainly to get rid of one top level directory. But this will
also be useful when there are tests of the embedding API.

test/language/comments/block.wren

@@ -0,0 +1,5 @@
+// In middle of line.
+IO.print/* ... */(/* */"ok"/* */) // expect: ok
+
+// Nested.
+IO.print(/* in /* nest */ out */"ok") // expect: ok

test/language/comments/block_at_eof.wren

@@ -0,0 +1,2 @@
+IO.print("ok") // expect: ok
+/* comment */

test/language/comments/line_at_eof.wren

@@ -0,0 +1,2 @@
+IO.print("ok") // expect: ok
+// comment

test/language/comments/only_line_comment.wren

@@ -0,0 +1 @@
+// comment

test/language/comments/only_line_comment_and_line.wren

@@ -0,0 +1 @@
+// comment

test/language/comments/unicode.wren

@@ -0,0 +1,11 @@
+// Unicode characters are allowed in comments.
+//
+// Latin 1 Supplement: £§¶ÜÞ
+// Latin Extended-A: ĐĦŋœ
+// Latin Extended-B: ƂƢƩǁ
+// Other stuff: ឃᢆ᯽₪ℜ↩⊗┺░
+// Emoji: ☃☺♣
+
+// TODO: What about combining characters?
+
+IO.print("ok") // expect: ok

test/language/comments/unterminated_block.wren

@@ -0,0 +1,3 @@
+// expect error line 3
+IO.print("nope") /*
+oops

test/language/comments/unterminated_nested_block.wren

@@ -0,0 +1,4 @@
+// expect error line 4
+IO.print("nope") /* /* /*
+*/
+oops