* src/preproc/pic/troff.cpp (troff_output::simple_circle,

* src/preproc/pic/troff.cpp (troff_output::simple_circle,
troff_output::simple_ellipse, troff_output::simple_arc,
troff_output::simple_line, troff_output::simple_spline,
troff_output::simple_polygon): Insert a space before arguments.
(troff_output::set_fill): Emit `\&' before `\D'Fg...' since the
latter doesn't produce a node, so the following `.sp -1' would do
the wrong thing.
Don't emit `.sp -1' after \M.  This also doesn't produce a token
(and we don't have to care about compatibility mode).
(troff_output::set_color, troff_output::reset_color): Don't emit
`.sp -1' after \M and \m.

* src/roff/troff/input.cpp (old_have_input): New global variable.
(input_stack::get): Handle `old_have_input'.
(process_input_stack) <token::TOKEN_NEWLINE>: Call
`trapping_blank_line' depending on `old_have_input', not
`have_input'.