Release 1.5.4

This release of LOOS includes several improvements and bug fixes.
First, the build system has better support for other linux
installations (i.e. Ubuntu and SUSE). An issue with SCons trying to
invoke doxygen, even though the built docs are bundled with the
release, has been fixed. A missing definition on Debian systems that
afflicted the parser has also been fixed. Improvements include a much
faster algorithm in the contact-time tool, support for user-defined
HCA parameters in the ENM tools, and special handling when the spring
constants go negative in the ENM tools. For more details, see the
ChangeLog in the distribution.