Add map generation in constructor.
Travis: set verbose output on test failure.
Merge pull request #40 from Neki/topic/bf_verbose_log_output

Travis: set verbose output on test failure.
Add the no_download option to the build process.
Merge pull request #41 from Neki/topic/bf_build_option_no_downloads

Add the no_download option to the build process.
README.md: fix links to Travis and Coverity.
Add test for map generation.
Merge pull request #38 from Neki/topic/world_create_map

Add map generation in constructor.
Handle event ACK on the client.
Fix the server-side event buffer.

Apart from simplifying the code, this fixes a confusion between client
id and event id : contrast
event_cache_.erase(it->first);
with
event_cache_[client_id].erase(it);
It also fixes dropping all events in a packet if one event ID was
already processed.
Add the correct namespace for the Direction enum.
Clarify log message.
The server can now send ACK in response to event packets.

Note that if the ACK is lost, no more ACK will be sent until the client
sends a new event (with a new ID).