Add new "nghosts" field for keeping animation history (trails).

Tidy.

Add default case to ...::printvalue().

Lots of changes to support new time flow and additional
time-related GUI.  Probably not all there but at least somewhat usable.

Add new files kira_parti (Steve McMillan's glue to starlab),
sclock (clock), notify (notification service -- not yet used),
Fl_Log_Slider (log-scaled slider).

Glue code to read starlab (kira) files and interpolate particle positions
into partiview internal form.

Now use worldline.h from ${KIRA}/inc directory rather than
the one hidden deep in the source.

Don't report error if WORDS_BIGENDIAN is undefined -- config.h might
just /* #undef */ it.  Just assume undefined -> false.

Add default rules for .cc (and .C and .cpp) files -- not all versions of make
have them built-in.

We're little-endian if WORDS_BIGENDIAN is defined (in config.h) and set to 0,
so use #if rather than #ifdef to test endian-ness.