BOSTON - Voters in cities and towns with municipal elections this summer and fall, including Boston, would be able to cast their ballots by mail without an excuse or in person during early voting days under a compromise bill lawmakers filed Friday that also creates a new MBTA governing body. After allowing pandemic-era election policies to lapse on June 30, House and Senate negotiators reached a deal on a fiscal 2021 spending bill that effectively revives and extends the voting provisions until Dec. 15. The $261.1 million accord, which involves additional spending for the fiscal year that ended June 30, calls for $131 million to help stabilize the early education and care sector amid enrollment fluctuations and other COVID-created upheaval as well as $5 million to help launch a new police standards and training commission created in the December 2020 police reform law.