New feature: drag&drop.

Window always accepts files with extensions: ".dmp", ".dmp.gz", ".so".
Dumps are copied to folder in $XDG_DATA, shared library used to extract
debug symbols.
Bugfix in parsing user info from attached plist.

Cocos2d-x produces incorrect DOCTYPE when it writes dictionary into
plist. We workaround it to make possible parsing by QXml.