Add conformer and fingerprint generation scripts to path upon installation

[sethaxen]

e3fp is now a package that can be installed with setup.py or pip, so it no longer makes sense for e3fp/conformer/generate.py and e3fp/fingerprint/generate.py to be runnable scripts, as in the usual case, the user won't even know where these scripts are or that they are scripts.

However, it would be useful for the user to have scripts that perform these functions added to $PATH upon installation. It seems the proper approach for this is with the console_scripts entry point. This approach registers a specific method in the package so that it can be run as a command line application (see this, this, and this).