Carver MT: Update to version 1.1.8, various fixes

Bump version to 1.1.8
Remove the Boolean mode toggles and bgl related code
Remove some of the unused variables
Some code style tweaks
Translate some previously missed tooltips

Simplify some of the repetive code
Use a property group for some of the scene props

Fix crashes:
- If there are any selected objects that are not meshes
- Fix an error in master related to storing selection (invalid object)
- Fix memory leak on quiting Blender while the operator is running

Note:
Concerning the E722 Pep8 - Bare Except Warning since there is a notice
with a full exception it can be disregarded