(income received from compelled lease of property that was held as rental property is includible in income and the involuntary conversion rules of I.R.C. Sec. 1033 do not apply; on the question of whether I.R.C. Sec. 1033 applies to a temporary taking of property, IRS reasoned that it did not because a fee interest was not taken and proceeds allocable to property was in nature of rent taxable as ordinary income in year of receipt).