Added the portals

Portals are now implemented in the source code and in Hammer Editor.
Fixed the portals

Now they are detached from the unexisting client class.
Added the health regeneration

Now the player can regenerate its health.
Health not regenerating fixed

Now the health regenerates properly.
Fixed the Combine NPC

Fixed an error which crashed the game when the player got too close to a
Combine Soldier.
Source SDK 2013 MP removed

Removed the multiplayer branch for the Source SDK 2013.
.gitignore update

Now git ignores all *.unsuccessfulbuild files generated during
compilation.
Updated the TARDIS railing model
Updated the game statistics
Merge branch 'master' of https://github.com/FrontBack/Thirteen-Lives