provides a flexible orderable plugins render_filename with entrypoints

[jpcw]

Flexible orderable plugin system with entrypoints to extend or override render_filename. Multi-registration available, specific target callable with -r, --rdr-fname-plugin-target cli option.
Long version here : https://github.com/jpcw/mr.bob/blob/03aecc4d16c54fa0964544a978128223d7d7d345/docs/source/pluginauthor.rst

[domenkozar]

Is there a reason you didn't implement this as another hook? What is the different between a hook and a plugin?

[jpcw]

the reason is there is
1 -> no pre_render_filename hook possibility today.
2 -> We need this feature, the possibility to skip or continue rendering filename after the hook.
My PR provide both, that said i can submit a pre_render_filename hook capability in c.render
But i think keeping registration of future pre_render_filename hook provide extensibilty flexibility.

behavior could be :
we had a pre_render_filename hook.
it return filename and skip boolean.

the lookup on hook could be in this order :

• look in entry_points with order parameter (like plugin in this PR)
• look in [re_render_filename] .ini which permit to load a pre-render class provided in specific need via .py in bobtemplate/something/hooks.py

It will be more flexible :

• hook can be called via entry_point for any template if needed without specify it in .ini
• overrided in a specific template via .ini

What do you think about this design ?

[gotcha]

@domenkozar Should this be closed ?