Added new hooks to WindowBase.

[NEW] Added WindowBase.beforeUpdate() and WindowBase.afterUpdate().
[NEW] Added WindowBase.beforeRender() and WindowBase.afterRender().
Added lineheight to windows.

[NEW] Added lineheight to windows.
[NEW] Added sample window skin in developing.
[ENH] Now restrict the drawing area of windows.
[FIX] Fixed the calculation of WindowBase.calculateLineHeight().
[FIX] Fixed the calculation of command positions in WindowCommand.
Now will skip splash in debug mode.

[ENH] Now will skip splash in debug mode.
Fixed the calculation of line height in windows.

[FIX] Fixed the calculation of line height in windows.
[DEL] Remove lineheight attribution from windows.
Merge branch 'window-base-improvement'