'pastetoggle': Revert support for multi-key value (#6724)

Reverts commit 337b617

Closes #6716 at the expense of not being able to use a
multi-key 'pastetoggle' manually.

Multi-key 'pastetoggle' can still be used when inserting the entire
option into the typebuffer at once (though the use here is
questionable).

Also remove those tests to do with waiting for the completion of
'pastetoggle' and mention in the documentation that 'pastetoggle'
doesn't wait for timeout.

runtime/doc/options.txt

@@ -4368,7 +4368,8 @@ A jump table for the options with a short description can be found at |Q_op|.
 	Note that typing <F10> in paste mode inserts "<F10>", since in paste
 	mode everything is inserted literally, except the 'pastetoggle' key
 	sequence.
-	When the value has several bytes 'ttimeoutlen' applies.
+	No timeout is used, this means that a multi-key 'pastetoggle' can not
+	be triggered manually.
 
 						*'pex'* *'patchexpr'*
 'patchexpr' 'pex'	string	(default "")

src/nvim/getchar.c

@@ -1908,7 +1908,7 @@ static int vgetorpeek(int advance)
           }
 
           if ((mp == NULL || max_mlen >= mp_match_len)
-              && keylen != KEYLEN_PART_MAP && keylen != KEYLEN_PART_KEY) {
+              && keylen != KEYLEN_PART_MAP) {
             // No matching mapping found or found a non-matching mapping that
             // matches at least what the matching mapping matched
             keylen = 0;

test/functional/options/pastetoggle_spec.lua

@@ -6,32 +6,35 @@ local command = helpers.command
 local eq = helpers.eq
 local eval = helpers.eval
 local sleep = helpers.sleep
+local expect = helpers.expect
 
 describe("'pastetoggle' option", function()
   before_each(function()
     clear()
     command('set nopaste')
-    command('set pastetoggle=a')
   end)
+
   it("toggles 'paste'", function()
-    eq(eval('&paste'), 0)
+    command('set pastetoggle=a')
+    eq(0, eval('&paste'))
     feed('a')
     -- Need another key so that the vgetorpeek() function returns.
     feed('j')
-    eq(eval('&paste'), 1)
+    eq(1, eval('&paste'))
   end)
-  it("multiple key 'pastetoggle' is waited for", function()
-    eq(eval('&paste'), 0)
-    local pastetoggle = 'lllll'
-    command('set pastetoggle=' .. pastetoggle)
-    command('set timeoutlen=1 ttimeoutlen=10000')
-    feed(pastetoggle:sub(0, 2))
-    -- sleep() for long enough that vgetorpeek() is gotten into, but short
-    -- enough that ttimeoutlen is not reached.
-    sleep(200)
-    feed(pastetoggle:sub(3, -1))
-    -- Need another key so that the vgetorpeek() function returns.
-    feed('j')
-    eq(eval('&paste'), 1)
+
+
+  it('does not wait for timeout', function()
+    command('set pastetoggle=abc')
+    command('set ttimeoutlen=9999999')
+    eq(0, eval('&paste'))
+    -- n.b. need <esc> to return from vgetorpeek()
+    feed('abc<esc>')
+    eq(1, eval('&paste'))
+    feed('ab')
+    sleep(10)
+    feed('c<esc>')
+    expect('bc')
+    eq(1, eval('&paste'))
   end)
 end)