FindIceT.cmake did not really do anything that CMake does automatically
with configure files.  To ge the automatic CMake stuff to work, I
renamed ICETConfig.cmake to IceTConfig.cmake.

All UseICET.cmake really did was add the include directories and link
libraries for everybody.  Since you really should be using
target_link_libraries anyway, this only left the include directories.
It's just as easy to add the include directories as it is to include
the use file.