Right-left buttons differentiation

Left | Right
-----|--------
mousedown | rightdown
mouseup   |  rightup
mouseupoutside   |  rightupoutside
click   |  rightclick
__isDown   |  __isRightDown

Names can easily be changed from the code.
Right-left buttons differentiation

Left | Right
-----|--------
mousedown | rightdown
mouseup   |  rightup
mouseupoutside   |  rightupoutside
click   |  rightclick
__isDown   |  __isRightDown

Names can easily be changed from the code.
Right button docs
Merge pull request #905 from DebanVG/dev

Right-left buttons differentiation