(plaintiff’s predecessor in ownership of tract bought tract from seller with seller reserving one-half of mineral rights and deed was recorded; plaintiff bought tract “save and except” the reserved one-half mineral interest and deed recorded; land subsequently divided into lots with the deeds using various language to point out the reserved mineral rights; plaintiffs executed oil and gas lease with energy company to lease the reserved mineral interest; energy company later became concerned that plaintiffs didn’t actually own undivided one-half of mineral interest; plaintiffs filed trespass action against lot owners to determine title to mineral interests; trial court ruled for lot owners; on appeal, deed language did not effectively reserve the mineral estate).