patches for line geometry

Hello Gautam. Here are some patches to get you started on fixing up the
support for line objects. The patches came from my sort-of-rev-locked
development tree frozen on 980408, which should/might apply cleanly to a
v6.3.2 source tree.

To apply:
1) untar the enclosed file into the main tree (i.e. in "src/..")
2) cd to the new directory patch.980501/
3) run patch on each file: "patch < geo_ops.c.patch" etc.
- check patch's comments to ensure the patches applied cleanly
4) cd to ../src
5) do a "make clean install"
6) do a "rm -rf ../data"
7) do an initdb

Some of the stubs you need will now be defined in the catalogs. At the
moment I put blocks of "#ifdef LINEDEBUG" around the new code, calling
elog(ERROR,). Just remove the #ifdefs and the elog messages and start
coding.

Before submitting as patches to the Postgres development tree we will
want to get a new snapshot and move around some of our new definitions
in the catalogs (reassign some of the OIDs). The post-v6.3.2 catalogs
look slightly different and probably conflict a little bit.

Anyway, let me know how it is going. Ask if you have any questions...

Have fun.

- Tom