Key binding in OS X

The HTML Visual view supported key binding since v2.5.2

Currently, some unchangeable key bindings are CTRL + other key.
But the COMMAND key is generally used in OS X platform. So I decide to make this change in next version.

I also plan support following commands in next version:

• Select Previous/Next Element (ALT+CTRL+Left/Right)
• Select Enclosing Element (ALT+CTRL+Up)
• Restore Last Selection (ALT+CTRL+Down)

Unfortunately, the key binding of these commands are defined for editor. I cannot get key binding when program running. Finally I may use the static binding. (Of course, replaced CTRL by COMMAND key for OS X platform.)

Please let me know if you have other suggestion. Thanks!