Add tools and move files to distinct folders

I think I’ve found a maintainable solution for #1 *without* creating extra SVG files. In `tools` folder you can find two scripts for people who need the test tube only. Note that the scripts extract the tube from the **dark layer**. If @cobyism  updates the main SVG, all we possibly have to do is to update the test tube ID inside of [extract script](https://github.com/cobyism/jekyll-logo/blob/a0c46a62c183eaa1a4b89ab5faf894f5822d4758/tools/export-test-tube.sh#L12).

@cobyism please take an extra look at my descriptions, I’m not native English speaker.