Allow backslashes between tokens

Fixes #14

corpus/programs.txt

@@ -40,3 +40,13 @@ f=g   \
       (word))
     (command_name (word))
     (word)))
+
+=============================
+Escaped whitespace
+============================
+
+echo 1 \ 2 \ 3
+
+---
+
+(program (command (command_name (word)) (word) (word) (word)))

grammar.js

@@ -41,7 +41,7 @@ module.exports = grammar({
 
   extras: $ => [
     $.comment,
-    token(choice(/\s/, '\\\n')),
+    /\\?\s/,
   ],
 
   word: $ => $.word,

script/known-failures.txt

@@ -19,7 +19,6 @@ examples/bash-it/completion/available/packer.completion.bash
 examples/bash-it/completion/available/vault.completion.bash
 examples/bash-it/completion/available/docker.completion.bash
 examples/bash-it/completion/available/tmux.completion.bash
-examples/bash-it/completion/available/virsh.completion.bash
 examples/bash-it/completion/available/apm.completion.bash
 examples/bash-it/completion/available/git_flow.completion.bash
 examples/bash-it/lib/preexec.bash
@@ -38,4 +37,3 @@ examples/bash-it/themes/nwinkler_random_colors/nwinkler_random_colors.theme.bash
 examples/bash-it/themes/mbriggs/mbriggs.theme.bash
 examples/bash-it/themes/kitsune/kitsune.theme.bash
 examples/bash-it/themes/doubletime/doubletime.theme.bash
-examples/bash-it/themes/duru/duru.theme.bash

src/grammar.json

@@ -2133,20 +2133,8 @@
       "name": "comment"
     },
     {
-      "type": "TOKEN",
-      "content": {
-        "type": "CHOICE",
-        "members": [
-          {
-            "type": "PATTERN",
-            "value": "\\s"
-          },
-          {
-            "type": "STRING",
-            "value": "\\\n"
-          }
-        ]
-      }
+      "type": "PATTERN",
+      "value": "\\\\?\\s"
     }
   ],
   "conflicts": [],