Add NERDToggleCheckAllLines option to NERDCommenterToggle (preservim#334

)

Udate version and date strings

Add multi-line comments for Elm (preservim#283)

Technically the minimum necessary syntax for block comments requires
only a single hyphen (`-}`, `{-`), but I have found that using a double
hyphen plays a bit more nicely with the elmcast/elm-vim auto-formatting.
Further, uncommenting when using the single dashes leaves an extra level
of indentation (again, when using elmcast/elm-vim).

Bump release number for the benefit of plugin managers that update to…

… tags

update version to 2.2.3

switch to version 2.2.2

switch to 2.2.1

switch to version 2.2.0

add support for xquery

change version to 2.1.17