Simplify xml.etree.ElementTree loading

[mitya57]

cElementTree is a deprecated alias for ElementTree since Python 3.3. As we are now supporting only Python ≥ 3.5, we do not need to use it.

The version check is also no longer needed. The module has version 1.3.0 since 2010, so even Python 2.7 and 3.2 have it (see python/cpython@f15351d938e76c4b).

[waylan]

Simplifying the code by removing old cruft like this is great. However, the cruft has only been half removed. See my comments below for what need sot happen before this can be accepted.

[mitya57]

Now that we deprecated this, I had to update a lot of internal code. Commit 0f48d17 deprecates the old markdown.util.etree wrapper, commits 80729a3 and 8b1f49a make the replacements, and commit 3b7a55b updates the documentation.

[waylan]

This looks good. However, one thing is bothering me. Sometimes we import as etree and other times we don't do the as etree bit. Lets be consistent throughout the lib.

[mitya57]

Ok. I decided to go with the as etree form as it is shorter and requires less changes throughout the code.

[waylan]

We should probably add a note to the release notes informing extension devs that markdown.util.etree is deprecated and that they should import xml.etree.ElementTree directly. With that small change, I think this is ready to go. Nice work.

[mitya57]

Done in 01ca739. Please check if the wording is fine.

[waylan]

Please check if the wording is fine.

It was pretty good. I made a few adjustments to the first sentence for consistency ("some.module.path module" requires the article "the" but if you leave out the word "module" then you also should leave out the article). The other changes were mostly additions which I probably wouldn't have bothered with if I wasn't already making changes.