stop trying to handle memory allocation errors
allow to change the bufferization mode for each route
add http_route_options_init()
refactor connection handling

There was a lot of cases where errors where not correctly handled. This is
still the case.

The current code should now handle interruptions (i.e. the case where an error
occurs after the request handled has already been called at least once in an
asynchronous way).
fix chunk parsing
give access to the address string of each connection
give access to the message content length
cosmetic
export http_set_error() for content decoders