Added a regression test for issue #1446: Line number in runtime warnings is one greater than the actual line number.
Fixed two places where RubyWarnings was printing lineNumber+1 instead of the actual line number.  This fixes issue #1446.
ThreadContext.gatherCallerBacktrace: Got rid of several lines of code that were computing things that were not used.
Merge pull request #1450 from DavidEGrayson/warning_line_pull_request

Make warnings show the right line number