Since it is necessary to select strips before being able to split them(not counting the toolbar split function), a much-needed function is the ability to select all strips at the playhead quickly with a shortcut key. This patch adds that functionality, however, later, when a shortcut key is agreed on, it can be added in a separate patch.
The function is added to Select > Playhead > Under
Gif (ctrl+left mouse):
Add Equal as shortcut for select under playhead, and move Insert Gaps to backspace + ctrl.
All of the extend (+shift) functions are added to the left, right under functions.

