Replace many usages of Boost with std counterparts

[YakoYakoYokuYoku]

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• [x] I've followed the contributing guidelines to the best of my understanding
• [x] I've read and understood the contributing guidelines
• [x] I've formatted my code according to Natron's code style
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PR Description

What type of PR is this? (Check one of the boxes below)

• [x] Breaking change (fix or feature that would cause existing functionality to change)

What does this pull request do?

Prior to this PR Natron made usage of many features from the Boost libraries that were not present in the standard C++ library, things like smart pointers or bound functions for example. And now many of them were added to the standard library.

This PR replaces many of the used features of the Boost libraries with modern standard library and bundled utilities. Namely

• Smart pointers (e.g. boost::scoped_ptr with std::unique_ptr)
• String operations
• Math functions (e.g. boost::math::cbrt with std::cbrt)
• Bound functions
• Noncopyable subclassing
• C limits (std::numeric_limits templates are used instead)

Although Boost still remains in use due to the lack of an equivalent in the stdlib for bidirectional maps and the serialization library is still required because projects use its XML serialization, though both of these things might change in the future.

Show a few screenshots (if this is a visual change)

N/A.

Have you tested your changes (if applicable)? If so, how?

By building and running both Natron and NatronRenderer.

Futher details of this pull request

This PR was split in commits to ease the review process and can be separated into different PRs if requested.

[devernay]

Can you please make the PR on RB-2.4 to avoid code divergence (there may be another 2.4 release)

[devernay]

The reason is that we don't have a working RB-2.5 windows build yet

[rodlie]

The reason is that we don't have a working RB-2.5 windows build yet

I was very close last time I worked on it, but due to various reasons I was not able to finish it. I got very limited time this weekend, but I might have time to finish it on Sunday (no guarantee of course).

[YakoYakoYokuYoku]

Can you please make the PR on RB-2.4 to avoid code divergence (there may be another 2.4 release)

If it's going to be one last release of RB-2.4 then I don't think it would be worth to backport.

[devernay]

I should be a no-brainer to backport. The codes haven't diverged that much so far

[YakoYakoYokuYoku]

Merging in one day if no further objections, if another 2.4 patch release is really needed then I can open another PR, but in the case we have a 2.5 build for Windows then I'll not.