[Leapy] Drag power line

I added a visual feedback represented by a drag power line to let the player know how much is he dragging more easy.

I considered two opcion:

- The player is able to drag and release anywhere on the screen.

- The player is able to drag and release only clicking first the frog.

The second one let's you aim better but it constrain where you can drag and release and sometimes this may be annoying.

And since the second one is contained in the first one (you can click over the frog if you wan't) i went for that one.

Share your opinion about it if you wan't.

To achieve this i have to give credit to Muddy Wolf video (www.youtube.com/watch?v=Tsha7rp58LI)

I added the first if to the update method of the frog to set the initial and end points where to draw the line while you are holding down the left click and added the last line when you release the button to erase the line.

To draw the line i used the unity LineRenderer and made a script to render the line and erase it.