MediaList, FileSelect - selecting single file should just play it

[Ike]

Or add to current playlist, or replace playlist depending on setting; it now replaces playlist with whole album/folder (which becomes obsolete if we implement select all button on every screen)

[masafumi terazono]

fix b7b4ff0428bc90c66a17e0685ffdf962716fa071 [b7b4ff0] ひとまず、ファイル選択画面だけ実装

[masafumi terazono]

fix 2060e13ea6bb3bdf099389cf430f7dbc39f051c9 [2060e13]

全ての画面に適用