termview: remove built-in support for Ctrl-Shift-V
termview: remove built-in support for Ctrl-Shift-V

Allow to send commands such as <C-S-x> to neovim. This allows the user
to manually define Ctrl-Shift mappings from its configuration files.
As a result, this partially fixes #40.

jeanguyomarch/eovim,jeanguyomarch/eovim,jeanguyomarch/eovim