wlav
Do not use file globbing in the build system
This makes the build configuration more robust to added and removed files.
See also the analogous PR in ROOT, as well as the corresponding Jira ticket:
- https://github.com/root-project/root/pull/3259
- https://its.cern.ch/jira/browse/ROOT-5998
Like this, we also don't need to "comment out" whole source files with preprocessor macros, like the TPyClassGenerator. This also helps ROOT, which requires these sources, because then the sources can be used as-is.
I wouldn't uncomment the TPyClassGenerator file as it really can't compile at this point. It accesses ROOT headers directly rather than clingwrapper APIs. The point of that file was to make Python classes usable from Cling. It's a cute feature, but no-one really ever cared about it, since callbacks (through a C++ base class) are easier to deal with.
