- Extract the line-reading code in ProcessInput to a separate function (ReadLine...

- Extract the line-reading code in ProcessInput to a separate function (ReadLine) that the parser can call. Now line continuations (using ^ at the end of a line) and multi-line parenthesized blocks work.
- ReadBatchLine: Don't strip the trailing \n, the parser needs it. Remove handling of :labels and @quiet commands, now done by the parser.
- ReadCommand: Add a \n to the line. Move PrintPrompt call out, since the prompt shouldn't be printed for additional lines read in a command beyond the first.

svn path=/trunk/; revision=35530