Tidy RPM Cache script

Release Notes: This revision fixes a bug where the script would exit if an incorrectly-formatted regular expression was supplied in the exclude option. The compilation of the expressions has also been improved. This revision also fixes a bug where some packages with the '.' symbol in the filename were not identified as separate packages (e.g. openoffice.org-core and openoffice.org-writer). This revision contains no other functionality changes.

Release Notes: A bug in the results table formatting code that could cause the script to quit unexpectedly was fixed.

Release Notes: The script now only compares RPM package files with the same package name and architecture. If you want to disregard the architecture attribute (i.e. go back to the old behavior), then use the command-line option --ignore-arch.

Release Notes: The script has been renamed from 'rm_obsolete_rpms.py' to 'tidy-rpm-cache.py' to clarify its purpose and to distinguish from the functionality in RPM relating to obsolete package files.

Release Notes: All warnings related to RPM headers are now printed after scanning is complete. Printing of warnings can also be disabled. A bug where obsolete versions of packages would not be processed if only one package existed has been fixed.