Remove all references to formatcmd

Initializing the `formatcmd` variable in the default language support
scripts created a dependency to the `formatter.kak` script, which we do
not want. Examples of such cases are when users haven't loaded the
`formatter.kak` script, or when Kakoune runs its test suite and
selectively loads some language scripts for testing purposes.

rc/base/d.kak

@@ -111,7 +111,6 @@ hook global WinSetOption filetype=d %{
     hook window InsertChar \{ -group d-indent _d-indent-on-opening-curly-brace
     hook window InsertChar \} -group d-indent _d-indent-on-closing-curly-brace
 
-    set window formatcmd "dfmt"
     set window comment_selection_chars "/+:+/"
 }
 

rc/base/go.kak

@@ -92,8 +92,6 @@ hook global WinSetOption filetype=go %{
     hook window InsertChar \n -group go-indent _go-indent-on-new-line
     hook window InsertChar \{ -group go-indent _go-indent-on-opening-curly-brace
     hook window InsertChar \} -group go-indent _go-indent-on-closing-curly-brace
-
-    set window formatcmd "gofmt"
 }
 
 hook -group go-highlight global WinSetOption filetype=(?!go).* %{ rmhl go }

rc/base/perl.kak

@@ -118,7 +118,6 @@ hook global WinSetOption filetype=perl %{
     hook window InsertChar \{ -group perl-indent _perl-indent-on-opening-curly-brace
     hook window InsertChar \} -group perl-indent _perl-indent-on-closing-curly-brace
 
-    set window formatcmd "perltidy"
     set window comment_selection_chars ""
     set window comment_line_chars "#"
 }

rc/base/ruby.kak

@@ -161,11 +161,6 @@ hook global WinSetOption filetype=ruby %{
 
     set window comment_line_chars '#'
     set window comment_selection_chars '^begin=:^=end'
-
-    # Rubocop requires a filepath that will be used when generating the errors summary,
-    # even though it's reading anonymous data on stdin
-    # It also leaves an ugly separator on the first line on the output
-    set window formatcmd 'rubocop --auto-correct --stdin - -o /dev/null | sed 1d'
 }
 
 hook -group ruby-highlight global WinSetOption filetype=(?!ruby).* %{ rmhl ruby }

rc/core/c-family.kak

@@ -240,8 +240,6 @@ hook global WinSetOption filetype=(c|cpp|objc) %[
     hook -group c-family-insert window InsertChar \n _c-family-insert-on-newline
 
     alias window alt c-family-alternative-file
-
-    set window formatcmd "astyle"
 ]
 
 hook global WinSetOption filetype=(?!(c|cpp|objc)$).* %[

rc/core/python.kak

@@ -75,8 +75,6 @@ hook global WinSetOption filetype=python %{
     hook window InsertChar \n -group python-indent _python_indent_on_new_line
     # cleanup trailing whitespaces on current line insert end
     hook window InsertEnd .* -group python-indent %{ try %{ exec -draft \; <a-x> s ^\h+$ <ret> d } }
-
-    set window formatcmd "autopep8 -"
 }
 
 hook -group python-highlight global WinSetOption filetype=(?!python).* %{ rmhl python }