Allow immediate unit-conversion in ruleset

[danau]

Converting units happens at end-turn, so converting units always takes at least 1 turn, even if the required movement points is zero or if the requesting unit has more movement points than required for the conversion.
This behaviour is fine for many conversions, but I would like to have the option to also have some conversions that happen immediately (at the moment the player gives the convert-instruction) if the unit has sufficient movement points.

An example is the "Launch" of "transported Missiles" as described in http://forum.freeciv.org/f/viewtopic.ph ... a77dd9a2fb (I have those launches currently done using a convert, but that means that launching happens one turn before the launched unit can be used, instead of directly.)

[Ignatus]

We will have converting Lua-powered user actions in upcoming versions that may be immediate. But there is an idea to make all activities/actions dure zero or more turns, I posted about it here. I remember, something was supposed to be done about your question on Freeciv21 branch.

[CalAnirm]

Is there a specific reason you prefer certain unit conversions to be immediate, and have you considered the potential impact on game balance with this change?

[danau]

Is there a specific reason you prefer certain unit conversions to be immediate, and have you considered the potential impact on game balance with this change?

Yes, the example of conversion from "Transported Missile" to "Launched Missile" is an example where I feel it would be very undesirable to wait for a full turn before the launch of a missile actually happens.

The extra set of units also has mounted and unmounted versions of units. I like unmounting for some units to also take less than 1 turn.

And I expect the impact to be "ruleset defined" since the duration would be configurable (some conversions can still take multiple turns). Rulesets that don't want any immediate conversions would still have all conversions take at least 1 turn.