deleteSelection when an output node had multiple connections only the first one was deleted, needed a new function to return a vector of connections that are now looped and deleted at the end of delete selection.
few other minor additions and fixes.
add the extra functions for drawing gui elements
RoundedRectangle:
All draw rect functions now pass through roundedRectangle which uses a shader and can draw borders, and rounds the corners
Draw thick line:
draws a line thicker than 1 pixel, uses a geometry shader to do this
Draw Circle:
Draws a circle with a border parameter.
