Add explicit "# key" directive to legacy snippet collection before deprecating filenames-as-triggers

snippets/python-mode/__

@@ -1,3 +1,4 @@
 #name : __...__
+# key: __
 # --
 __${init}__

snippets/python-mode/class

@@ -3,6 +3,7 @@
 # contributor: Orestis Markou
 # contributor: Nishio Hirokazu
 # contributor: Yasser González Fernández <yglez@uh.cu>
+# key: class
 # --
 class ${1:ClassName}(${2:object}):
     """$3

snippets/python-mode/def

@@ -2,6 +2,7 @@
 # name: def
 # contributor: Orestis Markou
 # contributor: Yasser González Fernández <yglez@uh.cu>
+# key: def
 # --
 def ${1:name}($2):
     """$3

snippets/python-mode/defm

@@ -1,6 +1,7 @@
 # -*- coding: utf-8 -*-
 # name: defm
 # contributor: Yasser Gonz¨¢lez Fern¨¢ndez <yglez@uh.cu>
+# key: defm
 # --
 def ${1:name}(self, $2):
     """$3

snippets/python-mode/for

@@ -1,4 +1,5 @@
 #name : for ... in ... : ...
+# key: for
 # --
 for ${var} in ${collection}:
     $0

snippets/python-mode/ifmain

@@ -1,4 +1,5 @@
 #name : if __name__ == '__main__': ...
+# key: python-modeifmain
 # --
 if __name__ == '__main__':
     $0

snippets/python-mode/prop

@@ -1,5 +1,6 @@
 # contributor: Mads D. Kristensen <madsdk@gmail.com>
 # name: prop
+# key: prop
 # --
 def ${1:foo}():
    doc = """${2:Doc string}"""

snippets/python-mode/propg

@@ -1,5 +1,6 @@
 #contributor : Julio Carlos Menendez <godinblack@gmail.com>
 #name : _get_foo ... foo=property(...)
+# key: propg
 # --
 def _get_${1:foo}(self):
     return self._$1

snippets/python-mode/propsg

@@ -1,5 +1,6 @@
 #contributor : Julio Carlos Menendez <godinblack@gmail.com>
 #name : _get_foo ... _set_foo ... foo=property(...)
+# key: propsg
 # --
 def _set_${1:foo}(self, value):
     self._$1 = value

snippets/python-mode/while

@@ -1,4 +1,5 @@
 #name : while ... : ...
+# key: while
 # --
 while ${condition}:
     $0