Fixes invalid character in variable name $fish_cursor_replace-one (used by fish_vi_cursor[_handle]) by renaming bind mode 'replace-one' to 'replace_one'.
* Added new function for the default prompt mode
Now fish mode prompt will call fish_default_mode_prompt, this will solve #3641
* Added function description
* Change wording for documentation about default mode prompt
* Finish changes requested in code review