ASTPrinter: Support empty goto case;

support goto case; with out an expression.

currently running dscanner --ast std/d/parser.d fails with a segfault
Parser: Support {start,end}Location for ReturnStatement
Update astprinter.d

Removed baraces for single if expression
changed spaces to tabs
Merge pull request #166 from liranz/master

Small fix for goto case and addition to ReturnStatement