Stop updating (and deprecate) neubot.hh

After some testing, I decided that libneubot will be written in C++,
which leads to more-easily-usable SWIG-generated code.

So, stop updating neubot.hh and deprecate both neubot.hh and gen_cxx.
gen_*: process a sequence of tuples

This way, we can preserve the order in which classes are
generated and, hence, the dependencies.

Of course, also update libneubot.json accordingly.
gen_header: stop sorting functions by class name

I prefer functions to be generated in the order in which they
are defined in libneubot.json.
Merge branch 'gen_foo-love'
Makefile.in: stop rm `cat .gitignore`

It was not working as I expected it to work. That is, comments
are not magically stripped away.