Users also can now explicitly set the path to the private
header files by passing "QT_PRIVATE_HEADERS=$PATH" to qmake,
or force qmake to ignore the plugins by passing in an invalid
/empty path.

Reviewed-by: con

Always write "Qt Creator" space. Also, make sure lines are
broken at 80 characters.

Reviewed-by: con

Details:  Requested in irc.