BEAM shall use OS-specific appdata directory instead of always assuming '<home>/.beam'.

For Windows
    beamDataDir = "${appDataDir}\\{vendorId}\\${applicationId}";
where
    appDataDir = System.getenv("APPDATA"); // TODO - or "LOCALAPPDATA" ?
    if (appDataDir == null) appDataDir = "${userHome}\\Application Data";
    vendorId = "ESA";
    applicationId = "beam";

For Mac OS X
    beamDataDir = "${userHome}/Library/Application Support/${applicationId}"; // TODO - verify

For other Unixes
    beamDataDir = "${userHome}/.${applicationId}";