use new elm_win_window_id_get to return wayland-compatible surface id: terminology is now wayland-teamwork compatible
Add option to disable drag and drop

Enabling drag and drop on a desktop (!touch) is too cumbersome: we
aren't allowed to select part of the link anymore since it would start
the drag and drop operation.
fix solarized-light theme
improve debug logs
fix shift tab. Closes T358
it's time to set TERM to xterm-256color
256: have a config to choose whether to set TERM to xterm-256color
add -2/--256color option to set TERM to xterm-256color

Man page was modified accordingly.
compat: fix backspace

According to
http://invisible-island.net/ncurses/terminfo.ti.html#tic-xterm-basic ,
xterm sends ^H == \b == 0x08.