Remove submodules (snippet and yasmate)

* snippets:
* yasmate: Remove.
* README.mdown: Suggest yasnippet-snippets and yasmate as possible
things to download rather than submodules.
* yasnippet.el (yas-installed-snippets-dirn): Mark obsolete.
(yas-snippet-dirs): Remove `yas-installed-snippets-dir' from
default value.

.gitmodules

@@ -1,7 +0,0 @@
-[submodule "snippets"]
-        path = snippets
-        url = https://github.com/AndreaCrotti/yasnippet-snippets.git
-        branch = master
-[submodule "yasmate"]
-        path = yasmate
-        url = https://github.com/capitaomorte/yasmate.git

README.mdown

@@ -58,22 +58,15 @@ where you want YASnippet enabled.
 Yasnippet no longer bundles snippets directly, but it's very easy to
 get some!
 
-If you git-cloned yasnippet with the `--recursive` option you'll also
-download "git submodules" and find two subdirs under the main tree.
-
-1. `snippets/`
-
-    Points to [yasnippet-snippets] the snippet collection of
+1. [yasnippet-snippets] - a snippet collection package maintained by
     [AndreaCrotti](https://github.com/AndreaCrotti).
 
-    The default configuraiton already points to this dir, so to use
-    them, just make sure the submodule really was downloaded
-    (i.e. there are some files under `snippets/`)
+    It can be installed with `M-x install-package RET
+    yasnippet-snippets` if you have added MELPA to your package
+    sources.
 
-2. `yasmate/`
-
-    Points to a github repo of the [yasmate] tool, which is dedicated
-    to converting textmate bundles into yasnippet snippets.
+2. [yasmate] a tool which is dedicated to converting textmate bundles
+    into yasnippet snippets.
 
     To use these snippets you have to run the tool first, so
     [see its doc][yasmate]), and then point the `yas-snippet-dirs`
@@ -96,7 +89,6 @@ should be added like this to `yas-snippet-dirs`:
           '("~/.emacs.d/snippets"                 ;; personal snippets
             "/path/to/some/collection/"           ;; foo-mode and bar-mode snippet collection
             "/path/to/yasnippet/yasmate/snippets" ;; the yasmate collection
-            "/path/to/yasnippet/snippets"         ;; the default collection
             ))
 
     (yas-global-mode 1) ;; or M-x yas-reload-all if you've started YASnippet already.

snippets

@@ -1 +0,0 @@
-Subproject commit 3226ab8d879d2b892ec0a269d0cca4ae086aa7c3

yasmate

@@ -1 +0,0 @@
-Subproject commit 0543618bd34a6715918992f01161c118f136bb37

yasnippet.el

@@ -157,16 +157,14 @@
   (file-name-directory (or load-file-name buffer-file-name))
   "Directory that yasnippet was loaded from.")
 
-(defvar yas-installed-snippets-dir nil)
-(setq yas-installed-snippets-dir
-      (expand-file-name "snippets" yas--loaddir))
+(defconst yas-installed-snippets-dir (expand-file-name "snippets" yas--loaddir))
+(make-obsolete-variable 'yas-installed-snippets-dir "\
+Yasnippet no longer comes with installed snippets" "0.13")
 
 (defconst yas--default-user-snippets-dir
   (expand-file-name "snippets" user-emacs-directory))
 
-(defcustom yas-snippet-dirs (remove nil
-                                    (list yas--default-user-snippets-dir
-                                          'yas-installed-snippets-dir))
+(defcustom yas-snippet-dirs (list yas--default-user-snippets-dir)
   "List of top-level snippet directories.
 
 Each element, a string or a symbol whose value is a string,