into a form that CodeMirror can understand.

Issue #4803

Addresses #4771

https://vi.stackexchange.com/questions/6061

The current situation prevents to remove bindings from the default keymap in vim
mode. It is sometimes required to be able to delete them in order to do some
custom mapping.

Example:

1. The `h` binding is defined in the default keymap for moving left.

2. The user want to set the custom binding `h<character>` to behave like
   `r<character>`. It can do so with:

     CodeMirror.Vim.mapCommand('h<character>', 'action', 'replace', {},
                               { isEdit: true, context: 'normal' });

3. When the user press the `h` key, the code searches for all the keybindings
   matching it [1].

4. Two bindings are found:

   - The default binding `h` for moving left. This is a FULL match.
   - The user-defined `h<character>`. This is only a PARTIAL match as it is
     expecting another character.

5. The code is preferring FULL matches over PARTIAL matches whenever they are in
   competition [2]. The code then selects the move left action.

6. The way to let the user-defined binding take over is to let the user delete
   the default binding:

     CodeMirror.Vim.unmap('h');

   but this is not possible because it is not allowed to delete bindings from
   the default keymap [3].

This commit remove such differentiation by treating all bindings in the same
way, letting the responsibility to the user to not mess with the bindings he
needs.

[1] https://github.com/codemirror/CodeMirror/blob/ff84b9ee73b75851801bc4004b75e35fea6291cb/keymap/vim.js#L1098
[2] https://github.com/codemirror/CodeMirror/blob/ff84b9ee73b75851801bc4004b75e35fea6291cb/keymap/vim.js#L1099-L1103
[3] https://github.com/codemirror/CodeMirror/blob/ff84b9ee73b75851801bc4004b75e35fea6291cb/keymap/vim.js#L4182



Signed-off-by: Fabien Dubosson <fabien.dubosson@gmail.com>

In Replace mode (or Overwrite mode) it should still go backwards
without deleting characters.

and remove autocomplete bindings

Issue #3991

The Error after the while(true) loop is not reachable and should
be removed. The "this.iterator" property should be given an
initial value of 0. This fixes two warnings reported by Closure
Compiler.

cm.save() might not exist if CodeMirror is not created from a
textarea. This adds an additional check to prevent TypeErrors.

Closes #3806

zt was placing 40% of the line above the visible area, and zb was placing it too high.

According to http://usejsdoc.org/about-getting-started.html, jsdoc comments must start with /**

- Use 'unshift' instead of 'push' to ensure newly mapped commands come first (and hence take precedence over previously mapped commands)

https://github.com/codemirror/CodeMirror/issues/3268

https://github.com/codemirror/CodeMirror/issues/3237