The Texas oil town of Midland edged out Boston and San Francisco as the hottest real estate market in the country in April, while Houston stayed on the cooler side, a new report showed. Midland landed the top spot among 300 metro areas tracked by realtor.com’s Market Hotness Index, which measures time-on-the-market data and listings views per property. Homes in Midland currently list for a median of $299,000 on realtor.com. That compares with $749,000 for Boston and $1.29 million for San Francisco. It is $14,000 higher than Houston’s median list price.