[Therion] loch surface(s)

[marco corvi]

if i put two surface's it seems that therion
writes both in the lox file.
loch reads the first only. but it can flawlessly
read and display both (just replace the if with a
loop) ... although maybe they are treated as two
sheets of "The Surface".

that's fine and i can get nice dem with the cave
and surfaces for geological planar features ...

the bitmap is a bit of a problem though:
only the first surface bitmap is used (ok: can 
comment on that test and get around it).

the bitmap is applied to both sheets (=surface's). 

the bitmap "tiles" the surface, instead of being 
overlaid on it [not sure about this].

what i would like:
- exporting two or more surfaces
- marking one surface as "DEM" and clipping the others
  in Z to this, unless the option "-clip off"
- loch attaching the bitmaps to their grids.

replay to Alexander mail:
- for the fonts you can edit xtherion init file
  and set your favourite fonts. the file is well
  commented.
- for Xwindow error on loch, don't know: you may
  follow the instructions in the error message and
  debug the program, or provide the lox file that
  crashed it.

marco