[GRASS5] NVIZ updates

[Bob Covill]

Hello,

I have committed several changes to the ogsf library and nviz. The 
changes include:

1. Removing the old nviz startup script. Startup is now handled directly
by NVWISH (still called as nviz), which is now installed in GISBASE/bin
as nviz. The nviz command now behaves more like a GRASS command. Typing 
nviz -h will print out the typical usage report. Also, error handling is 
improved by by-passing the script.

2. I have cleaned up alot of the excess debug statements. The panel
loading messages are now buried with a DEBUG flag in nviz2.2_script.
They can be started by changing the flag at the top of the file. I have
added a "-v" (verbose) flag to nviz which turns on the opening 
disclamer/version (the default is off). I have also removed a few debug 
lines from ogsf.

3. I have added catches for vector (and sites) that are loaded with no
data in the current region. This was causing a segfault. An error
message should now be generated and the file unloaded.

4. I have added a catch for loading a raster that either does not exist
or is outside of the current region.

5. I have activated a preliminary version of the "Draw Ruler" function
in the scale panel. The activated options are the 4 corner checkbuttons. 
With some (or all) of these buttons selected press the "Draw Ruler"
button. This will draw a grey fringe with black outline around the
selected corner of the current DEM. For best results the raster should 
fill the current region. Options that need to be added are bottom 
elevation, grid increment, and color.

To apply the changes update both the ogsf library and nviz and rebuild.


-- 
Bob Covill