Added support for parsing huge trees

[Langdi]

I added support for parsing huge trees (either nested > 256 levels or just big nodes) as discussed in #110.

As suggested it can be disabled when passing huge_tree=False to the Selector. I do version checking to check for lxml 4.2 for support of the huge_tree option there. A ValueError is raised when parsing a huge document and:

1. lxml doesn't support the HUGE_TREE option or
2. huge_tree=False is passed to the Selector.

I think raising an Error here is okay, because the resulting DOM is not what one would expect. However, I'm fine with any changes to handling this.

There is a test case added that tests this new behavior.

[codecov[bot]]

Codecov Report

Merging #116 (aa93f88) into master (6451476) will not change coverage. The diff coverage is n/a.

@@            Coverage Diff            @@
##            master      #116   +/-   ##
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  Coverage   100.00%   100.00%           
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  Files            4         4           
  Lines          138       138           
  Branches        33        33           
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  Hits           138       138           

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[Gallaecio]

@Langdi Hey, this pull request seems close to being ready, do you plan to continue working on it?

[Langdi]

@Gallaecio Yes, I'll finish this up some time next week.

[Langdi]

Should be done now. I added the behavior as discussed above. Please notify me if there's something left to do, I'm a first time contributor.

[Gallaecio]

@Langdi Do you think you will have time to fix those two minor comments I left? Also, it would be great if you could rebase your changes to solve the conflicts with recent changes in master.

[Langdi]

@Langdi Do you think you will have time to fix those two minor comments I left? Also, it would be great if you could rebase your changes to solve the conflicts with recent changes in master.

Sorry, I thought because of the "Changes approved" and "Needs one more approval" that my job is done, and someone else just has to review this. I fixed those now.

[Gallaecio]

You assumption was quite correct :slightly_smiling_face: ; we still need someone else to review this, which may take some time.