Mark pop

This is my first time doing this, so I apologize if I have done it incorrectly.

I wrote a little function, mc/mark-pop, that allows you to set the location of your cursors by pushing marks onto the mark right (via "C-Space" or otherwise) and then popping them, realizing them as new cursor locations.

I like this hack as it allows me to carefully place the cursors allowing for fairly intricate changes (particularly on S-expressions).  For instance, I have a difficult time marking every S-expression in a list without mc/mark-pop (you cannot match on open parentheses as it would catch nested forms).

This kind of doesn't work with transient-mark-mode.  Also, I don't completely understand your test suite, so I simply mimicked some of the tests in edit-lines.feature.  My limited testing indicates that this works well enough.