pyclean, pycompile: use .communicate() instead of .wait() to avoid hanging `dpkg -L PACKAGE` in few situations

- some packages moved from Conflicts to versioned Breaks
- Homepage field added

* add "|| true" in postinst-pycompile

* ignore dh's -O option
* allow multiple -p options
* add -N option

* make sure pycompile binary is available at intall time
* do not require pyclean at uninstall time