💥 Rename def-package! -> use-package!

Calling this pivotal macro "def-package!" has frequently been a source
of confusion. It is a thin wrapper around use-package, and it should be
obvious that it is so. For this reason, and to match the naming
convention used with other convenience macros/wrappers, it is now
use-package!.

Also changes def-package-hook! -> use-package-hook!

The old macros are now marked obsolete and will be removed when straight
integration is merged.

modules/lang/org/contrib/dragndrop.el

@@ -1,7 +1,7 @@
 ;;; lang/org/contrib/dragndrop.el -*- lexical-binding: t; -*-
 ;;;###if (featurep! +dragndrop)
 
-(def-package! org-download
+(use-package! org-download
   :commands (org-download-dnd org-download-dnd-base64)
   :init
   ;; HACK We add these manually so that org-download is truly lazy-loaded

modules/lang/org/contrib/ipython.el

@@ -1,7 +1,7 @@
 ;;; lang/org/contrib/babel.el -*- lexical-binding: t; -*-
 ;;;###if (featurep! +ipython)
 
-(def-package! ob-ipython
+(use-package! ob-ipython
   :defer t
   :init
   (defvar +ob-ipython-local-runtime-dir nil)

modules/lang/org/contrib/present.el

@@ -11,7 +11,7 @@
 ;;
 ;;; Packages
 
-(def-package! ox-reveal
+(use-package! ox-reveal
   :after ox
   :init
   ;; Fix #1127, where ox-reveal adds an errant entry to
@@ -22,7 +22,7 @@
         org-reveal-mathjax t))
 
 
-(def-package! org-tree-slide
+(use-package! org-tree-slide
   :commands org-tree-slide-mode
   :config
   (org-tree-slide-simple-profile)