[GRASS5] Maximum number of categories

[Radim Blazek]

Bad news!

I have discovered, that number of categories for each element is stored 
as 1byte. It was enough when only one cat of each field was allowed.
Now each field may have many cats and 256 is not enough.

I think that there are already too many 5.7 vector files in use, 
so I must increase 'coor' format version (5.0->5.1) [1], and to handle more versions
for reading. Unfortunately it will not be possible to read new files in older versions
of GRASS 5.7. I'll add first the code for reading and after some 1-2 months also for writing,
to minimize problems.

Do you have other suggestions?
What other should be changed in coor format? Now for example:
- 'field' is limited to short
- 4 bits for element type 
See V1__rewrite_line_nat.

Thanks to faunalia.it, they reached the limit first.

Radim

'coor' format version has nothing to do with GRASS SW version!