This library was originally taken from:
http://www.superliminal.com/sources/RTree.zip
described on:
http://www.superliminal.com/sources/sources.htm
Copy of this file is in sources.htm
The current R*-tree implementation is based on
http://dbs.mathematik.uni-marburg.de/publications/myPapers/1990/BKSS90.pdf

Changes done in GRASS:
- files converted to unix line ends
- added this file 'README.grass'
- added Makefile and Makefile.alone
- added mail from Daniel Green is in 'MAILS'
- few modifications to get rid of compiler warnings, but warnings like:
    index.c:277: warning: `tmp_nptr' might be used uninitialized in this function 
    were left because need deeper revision if may cause problems, insetad of blindly init to 0/NULL
- '//' comments -> '/* */'
- printf() - > fprintf(stdout,)
- NUMDIMS set to 3
- test.c 2D -> 3D
- type RectReal: float -> double 
- log_pi set to constant
- added GRASS headers to all *.[hc] files
- changed to R*-tree, near complete rewrite