Fixed the tooltips offset.

This was coming from the fact of using the OS cursor only, as CEGUI considers
it being 0x0 in size, and then computes the offset badly in that case.
I thus added an empty 12x12 cursor and used it without hiding the system one.

I also removed a obsolete comments and explained another one.

Fixes #337
Made the portals used standard claimed tiles as ground tiles.

I also made a few NULL->nullptr changes.

Last part and fixes #323
Dropped the Culling Manager

Moved the RadialVector class into utils where it actually belongs.

I also dropped the culling manager dependencies, and the correponding console commands.

Closes #170
Part of #91
Applied code conventions to remaining files.

Tiles.cpp and StackTracePrint.cpp

Actually, I didn't change a lot in the latter as the members in the structure
should stay same-named than their system counter-part.

Closes #91
Merge pull request #409 from Bertram25/development

Some fixes...