Added GameMessage.

[NEW] Added GameMessage.
Added WindowMessage.

[NEW] Added WindowMessage.
The Game will initialize GameMessage when the game start.

[NEW] Now Game will initialize GameMessage.
[ENH] Improved WindowMessage.
Fixed the quitting problem in WindowMessage.

[FIX] Now the coroutine in WindowMessage will quit correctly.
Merge from master.
Moved to new apporach of Game.

[MOD] Moved to new apporach of Game.
[DEL] Removed useless parameters in WindowMessage.
Improved GameMessage and WindoeMessage more.

[NEW] Added GameMessage.position.
[NEW] Added GameMessage.POSITION_TOP.
[NEW] Added GameMessage.POSITION_BOTTOM.
[NEW] Added GameMessage.isBusy().
[NEW] Added GameMessage.getAllTexts().
[FIX] Fixed a metatable problem in GameMessage.
[DEL] Removed GameMessage.visible.
Moved font setting from GameMessage to WindowMessage.

[MOD] Moved font setting from GameMessage to WindowMessage.
Make love 0.8.0 compatible with love 0.9.0.

[ENH] Now hook love.graphics.setMode() and love.graphics.getMode().
Improved WindowMessage.

[ENH] The WindowMessage will be paused when the texts fill the window
and all texts are shown.
Merge branch 'master' into game-message