Configs moved from /etc/core to $HOME/core

A new change in the development version of CORE (svn snapshot) is that the CORE GUI will now use a $HOME/.core directory for configuration that it writes.

• the default scenario dir for imn files is now ~/.core/configs/
• existing ~/.core preferences file is moved to ~/.core/prefs.conf
• plugins.conf, servers.conf, and widgets.conf now live in ~/.core/
• the read-only /etc/core/core.conf file still exists, for configuring the daemon (cored.py)

This fixes bug #25 (http://code.google.com/p/coreemu/issues/detail?id=25)