Update TODO list

Update TODO list

Some comments on the removed items:
- Mmh's show does already invoke a pager
- The reverse action of `rmm' is: refile -src +trash l @
- Disjunct contexts are already possible (just set MMHC accordingly)
- We already generate the mh-chart man page
- Prompter can already be used to input the recipients. Use:
        Editor: prompter
        prompter: -nobody
        prompter-next: vi
- Comp: -nowhatnowproc is obsolete; use `-whatnowproc true' instead.
  (It puts an empty draft into the drafts folder.)
- Forw: Since we use MIME to forward messages, these todos are obsolete
- Mhmail is not considered to be a full-featured interface to MH
- We now do have RFC 2047 encoding of headers