Wrote documentation for proposed refactoring

[antonag32]

There have been previous talks about refactoring source code in this repository. This is my proposal. It is based on a single Abstract Class (supported by a Message data class) which all linters will inherit from. My main goals are:

1. Standardize arguments and common behavior across most if not all linters.
2. Increase code reusability
3. Propose an Architecture which brings performance benefits, reduced development time and helps solve actual (and future) issues.

This is a middle ground between two options that were previously discussed:

• every single check being a hook
• making a giant tool that contains all checks.

Checks will be separated into tools based on:

• type (Dependent or Independent (see dev.md))
• files (xml, csv, po)

The .md file contains all details about the proposed change.

[antonag32]

@moylop260 Can you review the proposal and tell me what you think please?