[folding] Show number of lines folded

Current when a block is folded it currently only show ellipses, which I think it could be improved by show the lines of code in the block.

e.g. (using Python as an example)

def printthis(printme):
    print(printme)
    print("how did it print?")

When the code above is folded, it is represented as:

def printthis(printme): ...

Instead of just "...", it would be very useful to display how many lines are folded.

def printthis(printme): ...(2 lines)...

With short block it is not too difficult to identify the number lines folded by looking at the line number, but for a larger blocks, it would aid significantly by showing the number of line folded.