add cursor with motion

[jake-stewart]

for example if you map this action to ga:

• gaw would add a cursor on the next word
• gaip would add a cursor for each line in the paragraph

should work in visual mode (add cursor for each line)

[jake-stewart]

mc.addCursorOperator

its not great though. only works line-wise since cant handle inclusive/exclusive. only works for a single cursor at the moment