Micro AIs: don't check for specific value of move rating

Don’t check whether rating equals (or doesn’t equal) -9e99 or the like,
verify that a valid move was found instead.  Also, avoid setting
variables to empty tables if not needed.
Restore instructions for VC dependencies
Fix CB-Scons target names
fix cb project file

First, rerverted changes starting with commit
09b0aad1f837353f80bb7319543053f5a9ae66a8, the other commits were
just fixups to that. The, manually went through the resulting diff
and added/removed files which I know of or think they actually should
be added/removed. And, of course, compiled and linked.
Add SDL2 specific files to VC project
Merge branch 'master' of https://github.com/aquileia/wesnoth into aquileia-master
SotBE S6: remove AI controller

It does not work with leaderless allied sides.
Update changelog
added FLAG_VARIANT6 macro, for use with ragged flags
added wmllint rule for FLAG_VARIANT6
Changed all mainline occurrences of {FLAG_VARIANT ragged} to {FLAG_VARIANT6 ragged}
Changelog entry
fixup "make level reflect start of scenario"

we change set_attr to set_attr_dup as gfgtdf pointed out
purge "record_change_controller"

we can use "change_controller" now instead because of the new
network adapter from gfgtdf
fixup scenario transitions

when the host transitions to the next scenario, in some cases he will
send "[start]" before the other clients even have the new scenario cfg
this means that the controller tweaks he send will hit them while they
are in linger mode or something, and the next scenario won't work.

we fixup the download_next_level function on the server side so that
it updates the level config when sending it out to the transitioning
client.

this fixes up commit fb726e0610af42fa815cf340fa68c570b8bef0d3
and bug #21931
update changelog
Merge branch 'master' of https://github.com/wesnoth/wesnoth
Bottleneck Defense Micro AI: code cleanup
Messenger Escort Micro AI: code cleanup
Messenger MAI: fix typo

Sigh.  Intentional typo for testing, forgotten to revert it.