Properly clear terminal on Cursive::clear()

[azat]

Using buffer.write().clear() over printer.clear() (which is self.buffer.write().fill(" ")) helps with properly clear the cursive screen area after invoking side TUI apps within it (i.e. vim)

Note, that this is not enough to clear the complete screen in case of using ShadowView.

[gyscos]

Hi, and thanks for the work!

I'm just concerned that this would cause excessive I/O in most cases. Maybe we need a different function specifically for when another application may have messed up the screen.

[azat]

Hi @gyscos!

I will be OK with a separate method, but AFAICS the clear is not a hot path, and usually called explicitly by user

[azat]

This is an example for a problem - https://github.com/gyscos/cursive/pull/831 (press e then exit from editor and then c - nothing will be cleared), hope this will help