0] Precondition: current folder, containing init_db.sql and curves2db.R
   must be readable by the postgres user (some other weird restrictions ...)

1] Initialization:
  a) log in as postgres user:
	      sudo -i -u postgres
	b) launch PostgreSQL shell:
	      psql
	c) execute init script:
	      \i /path/to/init_db.sql

2] Launch DB-filling script:
  a) check/tune parameters at the beginning of curves2db.R
	b) run the script

=====

WARNING: very slow for large datasets

read_db.R: example usage to read curves from DB