Added toggle option for Light and Lamp tools

Added toggle option for Light and Lamp tools. I had to do some weird
stuff in order not to break lights and lamps in existing saves / dupes.
( All lights would become non-toggle whereas GMod at the moment spawns
only toggle lamps )

I also changed lights to use VPHYSICS instead of PhysicsInitSphere,
because why not?
Merge branch 'master' of git://github.com/garrynewman/garrysmod into patch2
Fixed a bug with skin property
Merge pull request #137 from robotboy655/patch3

Fixed a bug with skin property
Update changes.html
Fixed collision property jumping

Should we make collisions and keep upright properties the way gravity
property is done?
Merge pull request #138 from robotboy655/patch3

Fixed collision property jumping
Adding NextBot Base
Added IsValid check because the player invalid.

http://puu.sh/2b7vy
Merge pull request #152 from Chewgum/patch-2

Added IsValid check because the player invalid.
Merge pull request #136 from Ghor/master

Fixed cleanup accumulating invalid entities.
Merge pull request #133 from robotboy655/patch2

Added toggle option for Light and Lamp tools
Update duplicator.lua

Fix for save errors
Lamp in Toggle mode by default - so it retains old behaviour
The light too
By moving __index into Lua I'm hoping we see a bit of a performance increase
__index Fixes..
 - return false/0 etc
 - entity needs 'Owner' specialisation for viewmodels
Adding Timer class
CurTime, RealTime, FrameTime don't need to be engine functions
Adding vgui_screens.txt so it doesn't get stomped by mounted content