Added the capacity of setting face image position.

[NEW] Added the capacity of setting face image position.
Added MINIMUN_LINE_HEIGHT constant.

[NEW] Added MINIMUN_LINE_HEIGHT constant.
[ENH] Improved calculate_line_height().
Moved calculate_line_height to WindowBase.

[MOD] Moved calculate_line_height to WindowBase.
Resolve the conflict.

[FIX] Resolve the conflict.