horizontal splitter taller for added comfort (Fitts Law) and style adjusted to preserve class / instance / Doc buttons functionality
working on reacting to double click
double click a class will open a new browser on it
lists reacting to #onItemDoubleClicked:on:
in HLRefereces, doble clicking on a method referencing a class will open a new browser on that method
double click on implementors, senders and method reference found will open a browser in that class/method
fixes #35