Make gen_c output more pretty
gen_c: the slot is now just a type
poller: Export the event_base and evdns_base
Add hooks and slots, break the API and the ABI
Mark NeubotPollable_close() as a destructor
Bring gen_cxx up-to-date and simplify the API a bit
Backport some functionalities from gen_python to gen_cxx
gen_cxx: small fixes
More work on gen_python
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