💥 Remove :feature category

:feature was a "catch-all" category. Many of its modules fit better in
other categories, so they've been moved:

- feature/debugger -> tools/debugger
- feature/evil -> editor/evil
- feature/eval -> tools/eval
- feature/lookup -> tools/lookup
- feature/snippets -> editor/snippets
- feature/file-templates -> editor/file-templates
- feature/workspaces -> ui/workspaces

More potential changes in the future:

- A new :term category for terminal emulation modules (eshell, term and
  vterm).
- A new :os category for modules dedicated to os-specific functionality.
  The :tools macos module would fit here, but so would modules for nixos
  and arch.
- A new :services category for web-service integration, like wakatime,
  twitter, elfeed, gist and pastebin services.

modules/lang/cc/README.org

@@ -23,7 +23,7 @@ This module adds support for the C-family of languages: C, C++, and Objective-C.
 + eldoc support (~irony-eldoc~)
 + Syntax-checking (~flycheck-irony~)
 + Code navigation (~rtags~)
-+ File Templates ([[../../feature/file-templates/templates/c-mode][c-mode]], [[../../feature/file-templates/templates/c++-mode][c++-mode]])
++ File Templates ([[../../editor/file-templates/templates/c-mode][c-mode]], [[../../editor/file-templates/templates/c++-mode][c++-mode]])
 + Snippets ([[https://github.com/hlissner/emacs-snippets/tree/master/cc-mode][cc-mode]], [[https://github.com/hlissner/emacs-snippets/tree/master/c-mode][c-mode]], [[https://github.com/hlissner/emacs-snippets/tree/master/c++-mode][c++-mode]])
 + Several improvements to C++11 indentation and syntax highlighting.