iTunes 12 Apple Music search: is there a way to play all songs returned by search?
In iTunes 12.3.1, you can play multiple songs from search results by playing one of the songs listed on the initial search results page -- the one divided into "Top Results" "Songs" "Albums" etc. iTunes will continue playing from your search results after the initial song.

However, you cannot play multiple songs automatically from the detailed search results, e.g. if you click on "Songs" to see the all of the matching songs, and play one from there, it will stop playing at the end of the selected song.