[postgis-devel] new postgis.sql generation procedure

[strk]

I've modified the Makefile to build postgis.sql 
from postgis.sql.in and postgis_old.sql from
the bunch of sql files.

I hope this way more people will test the new
sql generation procedure, and we'll soon be
able to stop sql files proliferation.

Let me know on any problems encountered.

Thanks

--strk;