bug fix with function is_var_name/1 to to return false when the name is underscore.
bug fix with function is_var_name/1 to to return false when the name is underscore.


tdb/wrangler,arcusfelis/wrangler,arcusfelis/wrangler,prowessproject/wrangler,bsmr-erlang/wrangler,andrzejsliwa/wrangler