Changes for version 1.06
- getppid() not supported on Win32 and RISC OS, so now we check if we're running those OSes, and don't don't it if we are.
- Two of the tests loop looking for free or used PIDs. But in some situations they can loop infinitely, so now guard against this. I think this will prevent the hang on Windows in RT#96998, but dealing with this properly needs more investigation and work.
- Proc::Pidfile - a simple OO Perl module for maintaining a process id file for the curent process