#939 Align objects to Center or Middle of another object

[brades]

Please add a similar function to many other graphic tools to allow aligning an object to the center of another object, or to the middle of another object. Usually Center represents a vertical alignment, and middle represents a horizontal alignment. There are many times I wish I could align something in this way, and I have to manually calculate the difference between the two objects to get them centered vertically or horizonatally.

[Emmanuel Puybaret]

Duplicate of request #929