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.
Added multiple implementations of FileResource.

This prepares the transition to using FileResource rather than JRubyFile
directly for any areas where both jars and regular files are to be
supported.
Merge pull request #1450 from DavidEGrayson/warning_line_pull_request

Make warnings show the right line number
Merge with jruby-1_7