The python auto doc does not work when building for the first time

[HugoStrand]

Dear Nils,

App4triqs has the same problem as tprf had. That the python autodoc does not find the built python modules when trying to rip out the doc strings. The workaround is the same:

cmake .. && make -j 4 && rm -r doc && make -j 4

the first make gives errors when building the sphinx doc. Removing the doc directory and building again triggers a rebuild of only the doc and now when the modules are compiled the autodoc works.

Please fix.

Best, Hugo