add some check_victory-related logging to engine/enemies channel

This seems likely to come in handy in the future... I have added
and removed debugging code like this several times :)
I think engine/enemies is a good channel for it which won't
clutter.
add an assert in random_generate_scenario

it's better than segfault.
mp create engine uses Team + # syntax when use_map_settings=false

The old behavior was that when use_map_settings=false, every side
would have team=# for some number. This causes problems because
config might secretly decide that that is an int, and cause string
comparisons to fail.

Whether or not that is a bug is a separate issue, it seems clearly
desirable for sides to always have a team name of the form
"Team #", to side-step the potential problems.

This fixes up problems which appeared after
4d73031680b8889ec70e42607016269f7c421da5
852b6981329a96055249c513477be0d43b2fcaa0
Merge branch 'fixup_mp_connect_names'
add a warning to mp_connect_engine

The code path indicated seems to cause corruption of the game
configuration -- it might be better to just assert(false) in this
case but I'll leave as a warning for now.
add some safety code and assertions to set_scontext_leave_for_draw

This is unnecessary but on the other hand it can't hurt, in case
someone changes the system later without realizing it would break
this.
add an assertion to lua that it is not catching unnamed exceptions

It swallows these exceptions, which is surely bad...