Add forgotten bugfix to list.

Noted by:	Matt Robenolt
don't need ps2pdf to generate graphviz pdf output

dot -Tpdf seems to work fine
Spelling
document bereq.uncacheable and beresp.uncacheable
document keep
document some more object variables
make bereq.uncacheable read-only outside backend_fetch

Writing to bereq.uncacheable in backend_response and backend_error would only
make sense in the context of a retry. In most real world cases, writing to
be*resp*.uncacheable would be intended in backend_response and backend_error.
Varnish version in master should be trunk.

Try to avoid confusing everyone, since "4.0.1" (really trunk) has
fresher data than 4.0.2 (proper 4.0).

Mostly important for the sphinx builds put online.
Include the Varnish version on panic
vcl_pass might return fetch, not pass

Spotted by: coredump