dbglog: Added seperate macro for enabling debug log. Receive ERR message on all channels by default.

You still need to register the channel in the usual way to receive both MSG and ERR messages.
OGAMEMP: Added dbglog channel GameMP
OLOG: Add GetTickCount()-time to debug message (Windows only)
Multiplayer: Fixed major sync issue in is_mp_sync

This issue was introduced in "96101eed6ad Implement network support using enet"
is_mp_sync was not waiting when not all players were ready.
OBATTLE: Let the host determine initial gamespeed for all clients.
Merge branch 'MicroVirus-is_mp_sync_fix'
Applied is_mp_sync_fix branch
VS2010: Moved OGAMEMP.cpp to filter 'multiplayer' (from 'client')
VS2010: Added ENABLE_DEBUG_MESSAGES preprocessor definition in Debug build

This will enable all ERR(..) and MSG(..) messages in Debug. Note that to receive
MSG(..) messages, you will have to enable the channel using the environment variables.

The messages produced are sent to stdout. By default, VS2010 does not show these, but
they can be redirected to a file.