SDL interface checked in

[Stan Shebs <shebs at shebs dot cnchost dot com>]

After thinking about it for a year, and hacking madly for the past
couple of weeks, I've just committed a working version of an Xconq
interface using the SDL library (www.libsdl.org).  SDL is a low-level
cross-platform graphics library that Loki uses to port Windows games
to Linux, and has been used in quite a few other projects as well.
So far it's been encouraging - pages of nasty X and tk code turn
into a single BlitSurface, with no apparent loss of performance.

To try this out with the CVS sources, configure with --enable-sdl,
then make all-sdlconq.  In the x11 objdir, you'll get an sdlconq
for which you *must* supply command args (no setup dialogs), and
which can only move units, no construction yet.  In fact, everything
except the map is missing, so you have to guess about survey/move
mode, etc.  Take a close look at the cursor (and ignore the extra
rect, it's for debugging), you'll notice that it's multi-color,
which X can't normally do; it's being managed by the program.

Next steps are to add the rest of the graphics bits, and then
to start on the big task of adding dialogs and control panels.
My original plan, to have a hybrid interface that used SDL for
graphics and tcl/tk for widgets, didn't work out so well in
practice, which means that interface elements will have to be
built using SDL.  There are a couple toolkits for SDL that I'm
going to look into.

Stan