Remove old 7z items, add new exe:

* Remove 7zUnicode.exe, will no longer be needed
* Replace 7z.exe with 7za.exe.  7z.exe needs  7z.dll, and their
  combined size is smaller than 7za.exe (since 7zUnicode.exe is no
  longer needed)
* Remove 7zCon.sfx, this was part of the auto-updating system for,
  and isn't needed anymore
* Remove 7z.dll since 7z.exe and 7zUnicode.exe no longer need it
Replace all instances of 7zUnicode.exe/7z.exe with 7za.exe
Remove all references to MSVC 2005 from installers
Remove prepackaged MSVC 2005 runtime files
7z command line change to output in UTF-8