cleanup up shift-reduce conflict code, both for correctness and error reporting
added backslashes as an allowable symbol in the scanner
added backslashes as the equivalent of forward slashes, but ONLY in paths
added support for using a backslash as an escaping mechanism
  -- you can escape *anything* except a foward or backward slash and it
     will treat it as a character, so you can now have variable names
     with any special character in them, such as "a (meters)" via
     "a\ \(meters\)".  IOW, this lets you avoid having to use the <>
     variable quoting if you don't need to specify a host, cycle, etc.



git-svn-id: http://visit.ilight.com/svn/visit/trunk/src@4653 18c085ea-50e0-402c-830e-de6fd14e8384