Rename "strip" option to "skip"

[chrispy-snps]

Markdownify's strip configuration option is described as follows:

strip - A list of tags to strip. This option can't be used with the convert option.

However, "strip" has a different meaning in Python, which is to remove whitespace from a string. This can be confusing.

This issue requests to rename strip to skip. Feedback is also welcomed on the option name, if there is something better than skip.

For compatibility, we can remap strip to skip for some period of time.

[AlexVonB]

Good point, never occured to me. skip is good. omit could be used, too. I vote for either, your choice. Maybe even skip_tags to make it more clear?

[AlexVonB]

As #208 said, maybe we need one option for "remove this tags completely" and one for "keep the content of the tag, but dont convert it to markdown". I propose skip for the first and contents_only for the second (not quite there, i think).

[chrispy-snps]

@AlexVonB - agreed. How about passthrough?