Correct display mode highlight keys

Add html display mode to the help documentation.
Correct html and hex display mode highlight keys (help used 'h' for hex).
Correct json display mode highlight keys.

libmproxy/console/contentview.py

@@ -137,7 +137,7 @@ class ViewXML:
 
 class ViewJSON:
     name = "JSON"
-    prompt = ("json", "j")
+    prompt = ("json", "s")
     content_types = ["application/json"]
     def __call__(self, hdrs, content, limit):
         lines = utils.pretty_json(content)

libmproxy/console/flowview.py

@@ -34,9 +34,13 @@ def _mkhelp():
                 [("text", ": automatic detection")]
             ),
             (None,
-                common.highlight_key("hex", "h") +
+                common.highlight_key("hex", "e") +
                 [("text", ": Hex")]
             ),
+            (None,
+                common.highlight_key("html", "h") +
+                [("text", ": HTML")]
+            ),
             (None,
                 common.highlight_key("image", "i") +
                 [("text", ": Image")]

libmproxy/console/help.py

@@ -57,9 +57,13 @@ class HelpView(urwid.ListBox):
                     [("text", ": automatic detection")]
                 ),
                 (None,
-                    common.highlight_key("hex", "h") +
+                    common.highlight_key("hex", "e") +
                     [("text", ": Hex")]
                 ),
+                (None,
+                    common.highlight_key("html", "h") +
+                    [("text", ": HTML")]
+                ),
                 (None,
                     common.highlight_key("image", "i") +
                     [("text", ": Image")]