[Insight-developers] Unfound include files on gcc/linux

[Paul Hughett]

I've started fixing a series of problems on gcc/linux where either
CMake or gcc can't find the right include files and which is fixed by
adding appropriate INCLUDE_DIRECTORIES(...) lines to the CMakeList.txt
files.  If you're working on the same issue, you might want to either
wait until I give the all clear, or coordinate with me.  I have been
checking in the new CMakeList.txt files as I get them to work.

I'm not sure why this problem wasn't found before, but if it's because
it's platform-specific, I might be breaking the build on other
platforms.  You have been warned!

Paul Hughett