[pca] Feature request, --debug messages to stderr

[Martin Paul]

Daniel,

> thanks for awesome pca.pl .. would you please make sure in future
> release of pca.pl, that --debug messages will be written *only on stderr
> rather then stdout?

Good idea, I guess, as it allows to separate normal and debug output. 
I've changed it in the development release of pca now (20091001-01).

There's a small disadvantage, though - to get combined output into a 
file (or piped into "more") one has to use ">&" and "|&" or "2>&1" now 
depending on the shell family.

Martin.