fix grammar
improve documentation
add "threadparent" field to JSON
make threadparents always return an array
--html-to: clicking on subject will lead to threadparent instead of threadleader
doc fix
more open work
add attribute mappers for tbody and dd

to silence common NOTE warnings ("$map_att does not contain entry for
'tbody'").
more open work
bug #4
unwrap header lines in decoded_headers: no good

breaks subject lines
add unwrapped_headers
streamline usage of headers, unwrapped_headers, decoded_headers methods
fix: unwrap with a space, not nothing, for headers that use mimewords

Wondering whether there *are* any rules for these things. How
complicated can it get?

Also, turns out using unwrapped_headers is actually good, as
decode_mimewords does not replace all whitespace in the line wrapping
with a space (it leaves tabs in).
fix: explicitely unwrap with " " in decoded_headers, too
fix if_header_anglebracketed: unwrap headers with ""

fixes bug #4 (ids broken up on line endings)
more open work
Mylock: sleep
Parallel: exit without cleanup
add mylock_free