Added hook when a player is starting to paste

This hook gives the possibility to get the pasting player and the entity list on a very easy way.
This hook fits perfectly to the already existing hook, when a player finished to paste a dupe.

I'm open for any suggestions or changes!

Thanks
Use this function instead http://wiki.garrysmod.com/page/hook/Run

The reason FinishPasting doesn't use hook.Run is because hook.Run didn't exist back then.