[1824] Strange message when disabling auto-actions after mining company exchanged

[ollybh]

Auto-actions in a stock round are disabled when another player exchanges a mine company for the presidency of a regional railway.

It is right that this exchange is classed as a shenanigan and auto-actions are disabled. However the message isn't very informative:

Disabled programmed action 'Buy BK from IPO until floated' due to 'Unknown action special_buy disabling for safety'

It would be better to implement a custom action_is_shenanigan? method and catch this type of action and output an improved log message.

[perwestling]

Indeed, I had not considered the special actions and 1824, so I will look into that later this month.