Allow units to be freely converted between different types of unit

[Glenalth]

From the unit admin page you can change Companies to Households. While this is primarily for when a company is actually changed to a household, it is sometimes used for correcting errors made by players.

It is missing functionality for: Household to Company Household to Event Group Event Group to Company Event Group to Household Company to Event Group

Adding a drop-down menu to the "type" section allowing a player to select the wanted type of unit would be ideal.

Alternatively, just using a circular Company -> Household -> Event Group -> Company method would let it be done with a similar button to the "Convert to Household" that already exists.