Loopcut and Slide Improvements

Some of my proposals were already posted at some point, but I wanted to get my own take on the topic and also suggest how I would implement the improvements.

- An option to insert the loop cut at the current mouse position instead of always being in the middle

- Be able to change the number of cuts with the mouse wheel after committing the cut

- An option to move multiple edge loops symmetrical.

This could be solved by holding a modifier key like CTRL.

For example: when inserting two edge loops, they are moved symmetrical when holding CTRL

when inserting three, the middle one stays at the center and the outer ones move when holding CTRL

...and so on.

The behavior could be the same as when using the bevel tool on an edge loop.

- An option to preserve the current curvature of the mesh, when inserting loops.

This is especially useful, when adding more details on organic models without altering the shape too much.

Edit: somehow my images don't show up, so please click on the links instead.

Edit2: images now visible