2013-03-26 Jonathan Hogg Version 1.3.0. Replace FD15 with F95 intrinsics. 2008-03-?? Version 1.2.1 Some comments reflowed to length < 73. 2005-02-22 Version 1.2.0. FD05 dependence changed to FD15. 2004-08-06 Version 1.1.0. ICNTL(7) used to allow normalized curvature to be tested. 2004-07-12 Version 1.0.0. Version numbering added. 2001-03-23 Initial version: Threadsafe version of IM01