Interactive SICP-JS: Improve readability + minor fixes

[samuelfangjw]

Description

1. Improved readability by altering max width, line-height and font size.

2. Fixed formatting issues on index page. Previously, title and contents were not aligned properly. Also updated adapters names.

3. Remove dead code from syntax highlighting library that was previously bundled by webpack.
   before:
   
   after:
   

4. Fix figure margins and text alignment. Figures now have margins on the top and bottom. Text alignment for code snippets no longer centered (left align now).

5. Simplify parsing of containers, defined as elements that have a title and hold child elements. Previously, tags such as SECTION, SUBSECTION, SUBSUBSECTION etc. were all handled separately, even though they are parsed in same way. After this PR, the tags will all be parsed as section tags.

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update
• Code quality improvements

How to test

Checklist

1 & 2: verify page is as shown in the screenshots
3: build the project using yarn build, the build/static/js folder should look like the screenshots in the description. Syntax highlighting should still work.
4: verify figures in chapter 5 (e.g. 5.1.1) are left aligned (was centre previously)
5: Verify pages load correctly and titles at the top of each page can be seen.

• I have tested this code
• I have updated the documentation

[coveralls]

Pull Request Test Coverage Report for Build 942821044

• 4 of 4 (100.0%) changed or added relevant lines in 3 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.008%) to 30.241%

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Totals
Change from base Build 942319078:	0.008%
Covered Lines:	3231
Relevant Lines:	9865

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💛 - Coveralls

[samuelfangjw]

Ready to merge after this PR is merged.

[martin-henz]

All looks fine