Consolidate directory creation.
Correctly install .SEQ file.
Add Makefile support for $(DESTDIR)
Try new install command.
Combine default with environment-supplied CFLAGS.
Use top-level changelog.
Respect CPPFLAGS.
perr() fixes.

* Compiler warnings
* Save errno across vsnprinf() call
Refactor privilege escalation functions to avoid compiler warnings.
Update packaging.

Modernised and greatly simplified.
Fix up various lintian complaints, override a warning.