[CMake] .txt file extension

[Vincent Scheib]

Hey,

I'm ramping up on CMake, and love several things about it.

The CMakeLists.txt .txt file extension is driving me nuts, though.
Mostly, because I'd like to syntax highlight it, but can't distinguish
it from other file types.

I'm going to modify my local source for this. Has anyone thought of a
replacement extension that might eventually be folded back into CMake
proper?