fix to ignore error in signal trap context, fails to get thread lock to Engine.emit
fix not to call Fluent::Engine.stop 2 or more times, for process group killed situation on foreground
fix to mark shutting down situation before actual shutdown
Stop using a cached unpacker for MessagePackEventStream.

Sharing a a single instance of MesspaPack::Unpacker between input plugins and
MessagePackEventStream instances is unsafe. A test case has been added
to prove how easy it is leak events with the copy plugin and multiple
output plugins.
Merge pull request #132 from tagomoris/ignore_log_emit_in_trap_thread

fix to ignore error in signal trap context
Merge pull request #137 from abecciu/copy-plugin-event-leak-fix

Fix copy plugin event leak and fix undefined Test::Unit::AssertionFailedError bug in ruby trunk.
Add msgpack 0.4.x test to out_copy
add command line option to suppress error logs with specified interval (to avoid fluentd error log storm)
Merge pull request #134 from tagomoris/suppress_exec_filter_log

add option to suppress error logs with specified interval
Merge pull request #133 from tagomoris/signal_handle_for_foreground

Signal handle for foreground
Check MessagePack version to prevent MessagePack 4 performance degression
Remove unneeded require
v0.10.34