Added few commands

Added /fly, /vanish, /tpahere, /tpdeny 
Enabled /tps from console
Yes, and it is bad in regard of item duplication (each player instance receives the same inventory loaded from disk, so two players have duplicate items); but it is needed during development. There is a plan to have a setting option, or a cmdline parameter to specifically allow this and normal servers will not have this set; the devs can then use it to check their stuff as needed.