All municipal corporations of the territory or state of Kansas, heretofore organized as cities, towns, or villages, containing not more than two thousand inhabitants (and not heretofore organized as cities of the second class), including cities of the third class organized in accordance with the provisions of the act of which this is amendatory, and including also all unincorporated towns (without regard to their population) which may now or hereafter be constituted a county seat of any county, shall be cities of the third class, and shall be governed by the provisions of this act; and all rights and privileges accrued under and by virtue of, or provided by, any act of the legislature of the territory or of the state of Kansas, before the day on which this act shall take effect, to any such municipal corporation, are hereby confirmed and preserved to such corporation, and the citizens thereof, respectively.