Improvements to the docs and boosting test coverage

[sn]

This pull request introduces several improvements across the codebase and documentation, focusing on code quality, developer tooling, and enhanced documentation for the GUMP PHP validation library. The most notable changes include the addition of PHP-CS-Fixer for code style enforcement, updates to the composer.json scripts for linting, and significant enhancements to the README.md to improve clarity and provide more examples.

Developer Tooling and Code Quality

• Added a .php-cs-fixer.php configuration file to enforce consistent PHP code style using PHP-CS-Fixer.
• Updated composer.json to include friendsofphp/php-cs-fixer as a dev dependency and added lint and lint:fix scripts for code style checks and automatic fixing. [1] [2]

Documentation Improvements

• Refined the README.md:
  • Removed emojis and simplified language for better readability in feature lists and tips. [1] [2] [3]
  • Enhanced code examples to use plain messages instead of emojis for validation results.
  • Added new sections documenting the singleton pattern and the field() helper method, providing practical usage examples for advanced users.
  • Added a contributors section with a dynamic badge, and removed redundant or overly promotional statistics and feature sections. [1] [2]
  • Fixed minor formatting and spacing issues throughout. [1] [2]

Code Consistency and Minor Refactoring

• Standardized code style in CI scripts and main library:
  • Updated function definitions and array formatting in ci/boot.php and related scripts for improved readability and consistency. [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14] [15] [16]
  • Minor documentation update in gump.class.php to reflect current validator and filter counts.
  • Minor whitespace fix in gump.class.php.

These changes collectively improve the maintainability, usability, and developer experience of the project.