Retabbing the whole document. Now using STY variable to detect if you…

…'re in screen and TMUX variable to detect if you're in tmux. Added SCresize function to be able to resize the sclang output split/ region (which in turn just calls the screen and tmux primitives for resizing). Added the possibility to change between vertical and horizontal splits. Set the width/height of the split to a safe default value (30 blocks/lines). Fixed the way scvim in screen closes itself (now effectively kills the other regions when closing/restarting scvim). This commit makes scvim work in screen and tmux equally