add ew_alert (using ojw_alert one)
[experimental] add ojw_event

All the followings commits and files should be placed
somewhere else.
It will reorganize later
[experimental] add ojw_active_set
[experimental] add alert widgets
[experimental] add buttons widgets
[experimental] add base widget (base class)
[experimental] add completion widgets
[experimental] add traversable widgets
[experimental] add dropdown widgets
[experimental] remove old widgets implementations
[experimental] update makefile.options
[experimental] remove ojw_* (moved to ojwidgets)
adapt to the new ojwidgets
update ew_alert to last ojw_alert
update ew_button to last ojw_button
update ew_traversable to last ojw_traversable
update ew_dropdown to last ojw_dropdown
update ew_completion to ojw_completion
add ew_popup (eliom widgets version of ojw_popup)
use cmo instead of library for client side

when extracting to ocaml package