doc: Remove generated file examples.txt from index

Signed-off-by: Cyril Hrubis <metan@ucw.cz>
pywrap: Add swig typemap for GP_ProgressCallback

* Add typemap for GP_ProgressCallback
  - now a python function (or a touple of arguments) is converted to
    GP_ProgressCallback proxy transparently

* Add python progress callback documentation

Signed-off-by: Cyril Hrubis <metan@ucw.cz>