[REACTOS] Add features/usability additions.

[REACTOS] Add features/usability additions.

- Interface the TreeList code and populate it with the list of
  discovered disks and partitions. Code is adapted from USETUP.
  Also display the names of the disks.

- Display some installation settings summary, before doing the
  installation proper.

- Force the user to select a checkbox when (s)he acknowledges that
  ReactOS is alpha-quality software and may break on his/her computer
  or corrupt his/her data.

- Improve wizard pages transitions and buttons enabling/disabling.

- Press Shift-F10 to start a command-line (as in the 2nd-stage setup
  in syssetup.dll).

- Use some explicit UNICODE functions/macros.