Remove default insert mode movement bindings

Helix is first and foremost a modal editor. Willingness to support non-modal
editing is there, but it is not one that should be encouraged with the default
settings. There are an increasing number of users who are stumbling because
they are trying to use Helix as a non-modal editor, so this is an effort to
encourage new users to stop and take notice that Helix has a different paradigm
than VSCode, Sublime, etc. Users can still add these bindings back to their own
configs if they wish.

book/src/keymap.md

@@ -315,10 +315,12 @@ Mappings in the style of [vim-unimpaired](https://github.com/tpope/vim-unimpaire
 
 ## Insert Mode
 
-We support many readline/emacs style bindings in insert mode for
-convenience. These can be helpful for making simple modifications
-without escaping to normal mode, but beware that you will not have an
-undo-able "save point" until you return to normal mode.
+Insert mode bindings are somewhat minimal by default. Helix is designed to
+be a modal editor, and this is reflected in the user experience and internal
+mechanics. For example, changes to the text are only saved for undos when
+escaping from insert mode to normal mode. For this reason, new users are
+strongly encouraged to learn the modal editing paradigm to get the smoothest
+experience.
 
 | Key                                         | Description                 | Command                 |
 | -----                                       | -----------                 | -------                 |
@@ -327,23 +329,23 @@ undo-able "save point" until you return to normal mode.
 | `Ctrl-r`                                    | Insert a register content   | `insert_register`       |
 | `Ctrl-w`, `Alt-Backspace`, `Ctrl-Backspace` | Delete previous word        | `delete_word_backward`  |
 | `Alt-d`, `Alt-Delete`, `Ctrl-Delete`        | Delete next word            | `delete_word_forward`   |
-| `Alt-b`, `Ctrl-Left`                        | Backward a word             | `move_prev_word_end`    |
-| `Ctrl-b`, `Left`                            | Backward a char             | `move_char_left`        |
-| `Alt-f`, `Ctrl-Right`                       | Forward a word              | `move_next_word_start`  |
-| `Ctrl-f`, `Right`                           | Forward a char              | `move_char_right`       |
-| `Ctrl-e`, `End`                             | Move to line end            | `goto_line_end_newline` |
-| `Ctrl-a`, `Home`                            | Move to line start          | `goto_line_start`       |
 | `Ctrl-u`                                    | Delete to start of line     | `kill_to_line_start`    |
 | `Ctrl-k`                                    | Delete to end of line       | `kill_to_line_end`      |
 | `Ctrl-j`, `Enter`                           | Insert new line             | `insert_newline`        |
 | `Backspace`, `Ctrl-h`                       | Delete previous char        | `delete_char_backward`  |
 | `Delete`, `Ctrl-d`                          | Delete next char            | `delete_char_forward`   |
-| `Ctrl-p`, `Up`                              | Move to previous line       | `move_line_up`          |
-| `Ctrl-n`, `Down`                            | Move to next line           | `move_line_down`        |
-| `PageUp`                                    | Move one page up            | `page_up`               |
-| `PageDown`                                  | Move one page down          | `page_down`             |
-| `Alt->`                                     | Go to end of buffer         | `goto_file_end`         |
-| `Alt-<`                                     | Go to start of buffer       | `goto_file_start`       |
+
+However, if you really want navigation in insert mode, this is supported. An
+example config that gives the ability to use arrow keys while still in insert
+mode:
+
+```toml
+[keys.insert]
+up = "move_line_up"
+down = "move_line_down"
+left = "move_char_left"
+right = "move_char_right"
+```
 
 ## Select / extend mode
 

helix-term/src/keymap/default.rs

@@ -355,25 +355,6 @@ pub fn default() -> HashMap<Mode, Keymap> {
         "A-del" => delete_word_forward,
         "C-s" => commit_undo_checkpoint,
 
-        "left" => move_char_left,
-        "C-b" => move_char_left,
-        "down" => move_line_down,
-        "up" => move_line_up,
-        "right" => move_char_right,
-        "C-f" => move_char_right,
-        "A-b" => move_prev_word_end,
-        "C-left" => move_prev_word_end,
-        "A-f" => move_next_word_start,
-        "C-right" => move_next_word_start,
-        "A-<" => goto_file_start,
-        "A->" => goto_file_end,
-        "pageup" => page_up,
-        "pagedown" => page_down,
-        "home" => goto_line_start,
-        "C-a" => goto_line_start,
-        "end" => goto_line_end_newline,
-        "C-e" => goto_line_end_newline,
-
         "C-k" => kill_to_line_end,
         "C-u" => kill_to_line_start,