Remove blank lines

Trying to get the formatting to be at least somewhat consistent.
Lua AI: add new replay-safe action ai.synced_command()

This enables the execution of Lua commands from within the AI. The
commands are synced to be in the replay file as well, using a new
[command][lua_ai] tag.
Function call: ai.synced_command(command, x1, y1), where command is a
string containing the lua code and x1,y1 is an optional map location
that is the only allowed external variable used in the code string.
SotBE S6: rename transport AI candidate action file
SotBE S6: move unloading code into the AI

This is now possible with the new ai.synced_command Lua AI command and
means that the code does not have to be split between Lua and WML any
more.