Make the entries in the VSE - Select Menu make sense

PROBLEM
Select > Side of Frame... is not clear what frame it is referring to. And why ...?


SOLUTION
Handle and Channel are referring to visible elements in the UI. The visible indication of current frame is the Playhead, so rename Side of Frame... to Playhead.
The ... has been removed everywhere else in the UI, and should not be used here either.

PROBLEM
Box Select may be in consistency with a similar function elsewhere, but that naming was to distinguish it from Circle select. In the VSE, it doesn’t make sense to Circle select. A similar box selection function is used in Zoom and Set Preview Range, but they are not called Box Something, so it can’t be a consistency thing. What this function actually does is to select strips, which is not even clear from the current naming.


SOLUTION
Rename Box Select to Select Strips.

PROBLEM
Box Select (Include Handles) is messy and the above arguments apply here too.


SOLUTION
Rename Box Select (Include Handles) to Select Handles.