message: bump client version to 2.2.0.6
diff: #define CLIENT_VERSION_MAJOR 2
  #define CLIENT_VERSION_MINOR 2
  #define CLIENT_VERSION_REVISION 0
  -#define CLIENT_VERSION_BUILD 5
  +#define CLIENT_VERSION_BUILD 6
  // Converts the parameter X to a string after macro replacement on X has been performed.
  // Don't merge these into one macro!
  