[FIX] report_xlsx: Protect import + CamelCase class

[pedrobaeza]

This includes improvements in the README to avoid to generate modules depending on this one that generates problems:

• Protect the import to avoid the breakage when you don't have report_xlsx module accessible.
• Put the name of the class in CamelCase as PEP8 says.

[pedrobaeza]

cc @Tecnativa

[pedrobaeza]

@antespi, please review

[sbidoul]

👍 for the camelcasing of course

Adding the import error in the readme, I'm -0. At the end of the day, all this hackery is needed because we have suboptimal dependency management. When we have OCA/maintainer-quality-tools#343, it should become largely unnecessary (we probably need the same in rundbot)

[lasley]

👍

[yajo]

👍 👍 👍

[pedrobaeza]

@sbidoul, not all the people use or will use that deployment strategy, so I prefer to explicitly put this. I merge then.

[yajo]

@sbidoul I think the real solution would be that Odoo did not load uninstalled modules, and thus you could not install them without before parsing __openerp__.py and finding out external_dependencies, but that's not the way it works right now, so having an ImportError just for adding a repo to your addons path is annoying (under some deployment strategies, of course).

[sbidoul]

@yajo That would help yes, but IMO it's not the root cause. The real issue is that people just copy code arround (or git clone it or whatever), where they should use a proper mechanism to install it on the environments including dependencies. That's why I'm working so much on setuptools-odoo and pip... with very good results.