~/.muttrc: Remove {1,2,3} folder change keys.

Those are handled by the sidebar and quicknav.

.muttrc

@@ -66,9 +66,6 @@ set index_format="%4C %Z %{%b %d} %-15.15L %?M?(#%03M)&(%4l)?  %?y?[%.20Y] ?%s"
macro index = <tag-prefix>
macro index * <tag-entry>
## changing mailboxes
macro index 1 "<change-folder>=lu/INBOX<enter>"
macro index 2 "<change-folder>=htwk.imn/INBOX<enter>"
macro index 3 "<change-folder>=htwk/INBOX<enter>"
bind  index n next-unread-mailbox
# colors