[Insight-developers] txx policy

[Brad King]

Hello, all:

Since we are beginning to use explicit instantiations, the
ITK_MANUAL_INSTANTIATION flag may not always be left undefined now.  This
means that .txx files must be #included when instantiations are to be
created.  To prevent multiple inclusion, we must begin a new policy for
.txx files similar to that of .h files.  All txx files must be surrounded
by the following code:

#ifndef _NameOfFileWithoutExtension_txx
#define _NameOfFileWithoutExtension_txx

// rest of code in .txx source.

#endif

I used an emacs script to put this code around every txx currently checked
in (other than those in vxl) and commited the changes.  However, anyone
writing a new .txx source must add this code, just as when writing a .h.

-Brad