Add new template; for temporary templates

dotfiles/gittum/default/msg_tmp

+
+# use this file to define temporary template

dotfiles/gittum/main.gitconfig

   cma = commit --verbose --amend
   cmf = !sh -c \
         'git commit --edit --message=\"$(~/.gittum/bin/findcat msg_flake8)\"'
+  cmt = !sh -c \
+        'git commit --edit --message=\"$(~/.gittum/bin/findcat msg_tmp)\"'
   cmr = !sh -c \
         'git commit --edit --message=\"$(~/.gittum/bin/findcat msg_typo)\"'
   cmv = !sh -c \