Translations:Release notes 0.18/23/en

General Improvements on the code base

 * Tons of bug fixes.
 * Code refactor and cleaning. Get rid of duplicate code.
 * Fix a lot of typos in code and visible messages.
 * Python 3 compatibility fixes.
 * More unit tests where added.
 * Possibility to compile FreeCAD with external uptodate SMESH.