RFE: Let equipment go extinct more than once.

[HammerGS]

Noticed this with the recent Ammo tools Sleet01 made for princess.

We have equipment, ammos that can go extinct twice. Once in the SL era, than again in the Clan Invasion era. Currently we can only handle one return and one extinct date. It would be good to have the ability to do more.

Follow the Leader as an example. Went extinct again in 3054

    munitions.add(new MunitionMutator("Follow The Leader", 2, Munitions.M_FOLLOW_THE_LEADER,
            new TechAdvancement(TECH_BASE_IS).setTechRating(RATING_E)
                    .setAvailability(RATING_F, RATING_X, RATING_E, RATING_X)
                    .setISAdvancement(2750, DATE_NONE, DATE_NONE, 2770, 3046)
                    .setISApproximate(true, false, false, true, false)
                    .setPrototypeFactions(F_TH)
                    .setReintroductionFactions(F_FS, F_LC)
                    .setStaticTechLevel(SimpleTechLevel.EXPERIMENTAL),
            "368, TO"));