get_oauth_token: ask for DM access, too
get_oauth_token: ask for DM access, too

The app now defaults to read+write+DM. There is no (documented!) value
for the x_auth_access_type parameter which includes DMs; specifying
'x_auth_access_type=write' explicitly excludes DMs. So just don't
specify it.

This shortcoming in the docs at
https://dev.twitter.com/oauth/reference/post/oauth/request_token
has been reported to Twitter.

wjt/fewerror,wjt/fewerror