[New Addon] Better Tool Library

[knipknap]

Dependencies

• This Addon/workbench runs on:
  • [x] Most up to date stable release
  • [x] Most up to date development release
  • [x] Python 3 compatible
  • [x] Qt5 compatible
  • [x] Qt5 and Qt6 compatible (uses "import PySide" rather than "import PySide2")
• [x] Is this backward compatible with any previous version of FC? If so, please mention in the README.md
• [ ] Does this use 3rd party dependencies?
  • [ ] numpy
  • [ ] scipy
  • Please specify if there are any other dependencies below and in the README.md and package.xml files

README.md

• [x] Is [Markdown][Markdown-link] friendly
• [x] Has a Prerequisite or Dependencies section
• [x] Links to a LICENCE file (Note: FreeCAD uses LGPL2.1, most people choose that or GPL3)
• [x] Has a Screenshot and/or a section for screenshots
• [x] Links to a [FreeCAD Forum discussion thread][FreeCAD-Thread]

Misc.

• [ ] Do you keep a [changelog][Changelog]?
  If so, where?
• [x] Your Addon has an SVG based Logo?
• [x] Your Addon has a [package.xml file][Package_Metadata]?
• [ ] Edit the FreeCAD [External Workbenches][FC-ExternalWB-Wiki] wiki page

Housekeeping

• [x] Fixed typos in the code using [codespell][Codespell]. We recommend running: codespell -q 3
• [x] We recommend linting python code with PEP8. See [coding conventions][Code-conventions]

Github Related

• [ ] Does your repository use [Release tags][Github-Tags] ?
• [x] Repository has [topics][Github-Topics] which include FreeCAD Workbench Addon

Note: if your addon/workbench code doesn't reside on Github, please state the address where it is mentioned

[knipknap]

PR #265