Added Command Line Arguments

[foreachthing]

In commit 0d70c90 I've added the command line arguments listed below. This was requested in issue #2.

Arguments

To get a list of all possible arguments, type Recycling_Symbols.py -h.

• --path-openscad lets you define your own path to the OpenSCAD.com file.
• --codelist lets you define your own file with symbols to be created.
• --symbol lets you define just one single symbol (list won't be used). Example: --symbol 92 PLA 1 will create the symbol for PLA, number 99 within the recycling arrows.
• -m if argument is passed, the symbols will be mirrored (so you won't have to do that manually in your slicer software).