[Cmake] excluding files + keeping a clean tree

[John Biddiscombe]

Part 1)
When building vtk for example, there are a number of files which don't 
compile well (eg vtkVRMLImporter), and a few dozen other files which I will 
never use (EnsightReaders...for example)

I'd like to add in a
INCLUDE(  file containing my extra defs)
to several CMakeLists.txt files

Is there a command that I can use to EXCLUDE_SRC(....list) : exclude a list 
of source files from the already defined SRC list.

Part 2)
With the above in mind. I prefer to have a clean CVS tree so that when I do 
modify files for a specific purpose, I know exactly what's what. I'd prefer 
to not modify cmakelists.txt files directly, or if I must, at least keep 
the changes to a minimum. The above question could be solved by deleting 
some entries from the cmakelists files, but this may cause later conflicts 
when checking out from cvs (or just be messy). A single INCLUDE line would 
be easier to maintain.

What would be even easier is a command in the root directory cmakelists 
file such as

AUTOINCLUDE_LOCAL(myCMakelists.txt)

which would automatically look for a file myCMakelists.txt in every SUBDIR 
when it was searching for cMakelists.txt. If not present, it'd just skip 
it, but if present, would include it too. This'd make a clean way of 
modifying any subdirectory, (eg adding part 1's Exclude_SRC command) 
without CVS detecting any modified files, handy when working on CVS 
maintained projects. Is there a way of achieving this already, if not, any 
objection to adding it?

JB