remixed "Text Box" - customize and print without support

It's a remix of [JustinSDK 'Text Box'](https://www.thingiverse.com/thing:2194546)
this is a _real_ one, compared to the other 188 'remixes'

The main difference is using the letters to **cut out from the lid** (instead of adding), so it can be printed without support.

changes:
- added 'text_elevation': Instead of adding the letters on top of the lid with main 'thickness', I created the extra hight for the letters. It can also be **negative**, what means: it's easy to print without support if turning around the lid. The former 'thickness' is now 'wall_thickness'.
- added "letter spacing"
- the lid turns automatically 180º when 'text_elevation' is negative


I rendered 8 objects (2 version per each) but I printed only one (yes 'Zahnbürst' without ending e).
the difference of the 2 versions are:
- one with negative letter offset - they are not easy to see in the previews since the lids are turned for printability: the top on bottom
- one with positive offset (just because