Fix a couple of VS2012 build issues

I fixed a couple of minor hygiene issues with the VS2012 build.

* Correct version number in solution file so it opens in VS2012 when double-clicked.
* Add *.user to ignore list.
* Ignore and remove files generated by flex/bison during the build.

About the last, I'm not sure if this might screw up some other build configurations or something.  I see these files were commented out of .gitignore before; not sure why that was done.  If it's an issue, that commit can be left out.