Display rich rule description diffs

[fourls]

Prerequisites

• [X] This improvement has not already been suggested.
• [X] This improvement would be generally useful, not specific to my code or setup.

Engine area

Delphi IDE integration

Improvement description

The SonarDelphi rule descriptions make use of a special diff view syntax. SonarQube recognises these and runs a diffing algorithm to render them with full highlighting:

DelphiLint does not have a diffing algorithm implementation and so only displays these in a very rudimentary way:

DelphiLint should display these diffs in the same rich manner that SonarDelphi does.

Rationale

The current approach would bring DelphiLint in line with SonarQube for rule descriptions, and would greatly improve readability of these code snippets.

[fourls]

SonarQube's diffing logic is implemented in code-difference.ts in SonarSource/sonarqube. It defers the actual diffing algorithm to jsdiff, which is incompatible with the embedded IE browser.

This indicates that if we want diffing, we'll have to do it ourselves.

[fourls]

Fixed in 77e9e4c219b19b1f9d8a41d7c09ad51f650b28ac