don't overwrite "name" in mpconnect

and also remove unneeded code.
we now don't overwrite "name" (the name of the leader) in mp connect if
it given by the scenario.
We also fix a previous commit "don't generate 'user_description' on the
host" which caused that the AI algorithm wasn't shown to the clients.
don't remember which client controlls an ai side

in [multiplayer] side_controllers=
simplyfy wesnothd code.
remove debug info
fix leader names in mp

"name" is here the name of the leader, previously the flg manager set it
to the name of the faction.
change a comment
don't have "reserved_for" side attribute during the game

this attribute is only to be used during mp connect.
readd formulas is_human and is_ai callables
is_local_ai() || is_networked_ai() -> is_ai()