nvda root sconstruct: the release commandline option now only controls filenames...

nvda root sconstruct: the release commandline option now only controls filenames and whether NVDA's Python will run optimized, it does not affect nvdaHelper. There is now a new scons commandline option called nvdaHelperDebug. If you set this to 1, then vdaHelper will be built with asertions enabled, debug symbols, it will use debug libraries, and it will not be optimized.