Security checks
---------------
-- `refreshpofiles` uses `system()`, whose args have to be checked more
- thoroughly to prevent any security issue (command injection, etc.).
- > Always pass `system()` a list of parameters to avoid the shell.
- > I've checked in a change fixing that. --[[Joey]]
- Can any sort of directives be put in po files that will
cause mischief (ie, include other files, run commands, crash gettext,
whatever).