For atos specify the architecture and properly escape the path. When parsing the results read all the digits from the line number, not just the first. Don't abandon opening the file when only a filename is specified as atos only returns filenames, not filepaths.
#codereview michael.trepka
[CL 2093090 by Mark Satterthwaite in Main branch]
#ttp 330039 EDITOR: Platform-agnostic editor code depends on Windows-only VSAccessor headers
#detail Source code access is now extensible via plugins, so any new editors can be easily added.
#add Added SourceCodeAccess module that routes access via plugins.
#change Moved much of the old VSAccessor code into a new VisualStudioSourceCodeAccess plugin.
#add Added a counterpart XCode plugin & migrated the code from FSourceCodeNavigation (Applescript etc.) into there.
#remove Removed applescript for XCode access (it is now done via code).
#remove Removed source code access functionality from platform layer.
#add Added details customization for source code access settings, so users can choose their own accessor.
#remove Removed dependencies on VSAccessor.
#change Changed API in SWidget to not require building a string to be parsed, instead this acesses and forwards filenames & line numbers.
#extra Tested on Mac by Mark S.
reviewed by Andrew.Brown
[CL 2048697 by Thomas Sarkanen in Main branch]
