Slope annotation that reads from rotation angle

#http://www.onland.info/archives/2015/02/centerline_sym_jm16.php Centerline symbol with optional line and symbol at other end. Optional complete font list like in Jakub Chruscinski's version; not all fonts will look right without hacking the text offsets. Previous: 7-25-2002: CENTERLINE SYMBOL JAM70 12-16-2002: CENTERLINE SYMBOL RND 2006-06-20: CenterLine Sym JM9 CenterLineSym JM16 2014-10-14: Added Line option 2015-02-04: Added all fonts option