Feature: UI fixes and readability enhancements

[tgreyuk]

Motivation

Documentation could be improved by reducing clutter and removing repeated items. Also there is inconsistency of use of style to define types.

This feature makes several improvements to the UI with the aim to address these issues.

Improvements

• There is a mix use of backticks and italics for primitive and literal types for emphasis. All these types should consistently use backticks.
• Removing use of italics for reference types as can be hard to read.
• Removed parameter types inside function parenthesis as it can become hard to read with complex types and they are defined in params table just below anyway.
• Use h4 for 'Returns' and 'Defined in' headings to make more readable and consistent.
• Fixed nested heading structure under 'Type declarations' heading.
• Simplified Type parameter tables.
• Simplified class constructors.
• Some additional minor cleanups.