fix(runtime): clean up one-off scripts

Problem: Some runtime files no longer spark joy.

Solution: Kondo the place up.

Still sparks _some_ joy (moved to new `runtime/scripts` folder):
* `macros/less.*`
* `mswin.vim`
* `tools/emoji_list.lua`

No longer sparks joy (removed):
* `macmap.vim` (gvimrc file; not useful in Nvim)
* `tools/check_colors.vim` (no longer useful with new default colorscheme and treesitter)
* `macros/editexisting.vim` (throws error on current Nvim)
* `macros/justify.vim` (obsolete shim for `packadd! justify`)
* `macros/matchit.vim` (same)
* `macros/shellmenu.vim` (same)
* `macros/swapmous.vim` (same)

runtime/scripts/less.sh

@@ -0,0 +1,26 @@
+#!/bin/sh
+# Shell script to start Vim with less.vim.
+# Read stdin if no arguments were given and stdin was redirected.
+
+if test -t 1; then
+  if test $# = 0; then
+    if test -t 0; then
+      echo "Missing filename" 1>&2
+      exit
+    fi
+    nvim --cmd 'let no_plugin_maps = 1' -c 'runtime! scripts/less.vim' -
+  else
+    nvim --cmd 'let no_plugin_maps = 1' -c 'runtime! scripts/less.vim' "$@"
+  fi
+else
+  # Output is not a terminal, cat arguments or stdin
+  if test $# = 0; then
+    if test -t 0; then
+      echo "Missing filename" 1>&2
+      exit
+    fi
+    cat
+  else
+    cat "$@"
+  fi
+fi