Move BOM management and HTML functions to separate modules

[17o2]

Closes #151.

[17o2]

Moving the BOM modules to a separate file might be trickier than expected...

[kvid]

I know this is WIP, but in case these hints might help you:

• get_additional_component_table and manufacturer_info_field is not used for BOM and might rather belong to wv_gv_html.py.
• clean_whitespace is not used for diagram output. It is rather generic, but currently used for BOM.
• remove_links is rather generic and mainly used for diagram output, but also for .bom.tsv output.

[17o2]

Thanks, yes, I'm moving things around as I progress.

Currently, build_examples.py runs without errors, but BOM output is empty.

It seems things are getting lost inside generate_bom() when passing into from the bom_entries variable to bom. I need to figure out why both are needed; I haven't had a deeper look at the latest BOM code.
Update: this was a quick fix.

I think the BOM generation code has grown quite complex, so I need some time to understand it, and make sure we are not passing around more objects than needed, that functions end up in the correct modules, etc.

[17o2]

• get_additional_component_table and manufacturer_info_field is not used for BOM and might rather belong to wv_gv_html.py.

• get_additional_component_table is tightly linked to get_bom_index() and that one to the actual bom() function, therefore I will choose to leave it in wv_bom.py, at least until we refactor the BOM code, which should be a separate PR.
• manufacturer_info_field is also used in component_table_entry for generating the mini-BOM within a component node, and it's related to the typical BOM fields pn etc., so I think it also belongs in wv_bom.py. Also, it does not generate any actual HTML.

• clean_whitespace is not used for diagram output. It is rather generic, but currently used for BOM.
• remove_links is rather generic and mainly used for diagram output, but also for .bom.tsv output.

I agree they're generic enough to move to wv_helper.py since they are not really tied to BOM or HTML stuff.

[17o2]

build_examples.py now runs without errors, and the output is exactly the same as when using the dev branch.

Therefore, unless no glaring errors show up, I would like to merge this soon. Refactoring and optimization of the affected functions can happen in a later PR. Thanks!

[kvid]

I can verify that the output is unchanged when generating examples. I do have some simplifications of wv_bom.py in my local repo that I plan to push to a new PR when this is merged, as you requested.