Fixed MSVC compilation.
Fixed ODPacket::readPacket() as done by @hwoarangmy
Moved a const variable to the beginning of the file as requested by @hwoarangmy
Made the CEGUI.log file be part of the user data.

Fixes #358

I had to split the CEGUI::OgreRenderer::boostrapsystem() call in more small pieces
to set the log file name early enough.

The code should have an identical effect, though.
Merge pull request #360 from Bertram25/development

Fixed MSVC compilation + fix for 358