Julia: Make sure NEWS.md lists all 0.6 deprecations and breaking changes

[tkelman]

Reviewing the checklist I had in https://github.com/JuliaLang/julia/issues/17418 for the 0.5 release, pretty much the only thing we're missing for an 0.6 RC (other than #21470) is doing a final pass over NEWS.md and making sure all the deprecations and breaking changes that should be listed there are.

Check https://github.com/JuliaLang/julia/issues?utf8=%E2%9C%93&q=label%3Anews and https://github.com/JuliaLang/julia/issues?utf8=%E2%9C%93&q=label%3Adeprecation and https://github.com/JuliaLang/julia/blob/release-0.6/base/deprecated.jl#L117-L1325, make sure everything is listed.

[tkelman]

specific examples that had the news label, not yet mentioned in news (not a complete list)

• [x] #19771
• [x] #19779
• [x] #18444
• [x] #19901
• [x] #19900
• [x] #17155
• [x] #10946
• [x] #19786
• [x] #19636
• [x] #15850
• [x] #19811
• [x] #12274
• [x] #19594

[StefanKarpinski]

@Sacha0, you rock! Thank you for writing news for so many changes (especially so many of mine).

[Sacha0]

My pleasure, thank you for the kind words, and thank you for reviewing! :)

[Sacha0]

I culled the set of closed pull requests labeled news to those still absent from NEWS.md. The following such pull requests remain in need of attention:

• [x] #20345
• [x] #20248
• [x] #18342
• [x] #18159

[tkelman]

we should maybe rename the label to needs-news then if we're going to use it as a state tracker and remove it once added

[tkelman]

17439 was 0.5, #12807 is 0.7

[Sacha0]

17439 was 0.5, #12807 is 0.7

Updated --- thanks! :)

[Sacha0]

The above pull requests should cover news for all closed pull requests labeled deprecation that remain in need of attention, excepting the following LibGit2-related pull requests that I am not certain what to do with immediately (list formerly here consolidated below)

[Sacha0]

The above pull requests should cover news for all items in base/deprecated.jl, less

• [x] #19730
• [x] #20952 ?
  and the libgit2-refactor-related
• [x] #20435
• [x] #20135
• [x] #19935
• [x] #19878
• [x] #19660