move to subdirectory for shared worktree

diff --git a/.gitignore b/.mutt/.gitignore
similarity index 100%
rename from .gitignore
rename to .mutt/.gitignore

diff --git a/add-tickle-stamp b/.mutt/add-tickle-stamp
similarity index 100%
rename from add-tickle-stamp
rename to .mutt/add-tickle-stamp

diff --git a/alternates b/.mutt/alternates
similarity index 100%
rename from alternates
rename to .mutt/alternates

diff --git a/colours b/.mutt/colours
similarity index 100%
rename from colours
rename to .mutt/colours

diff --git a/headers b/.mutt/headers
similarity index 100%
rename from headers
rename to .mutt/headers

diff --git a/hooks b/.mutt/hooks
similarity index 100%
rename from hooks
rename to .mutt/hooks

diff --git a/keybindings b/.mutt/keybindings
similarity index 100%
rename from keybindings
rename to .mutt/keybindings

diff --git a/lists b/.mutt/lists
similarity index 100%
rename from lists
rename to .mutt/lists

diff --git a/muttrc b/.mutt/muttrc
similarity index 100%
rename from muttrc
rename to .mutt/muttrc

diff --git a/offline b/.mutt/offline
similarity index 100%
rename from offline
rename to .mutt/offline

diff --git a/sendmail b/.mutt/sendmail
similarity index 100%
rename from sendmail
rename to .mutt/sendmail

diff --git a/spam b/.mutt/spam
similarity index 100%
rename from spam
rename to .mutt/spam