Version 0.12.0 released

Minor update of Procedural Text Edit with focus on the CLI version.

• New optional path parameter `program` added to CLI. If present proceduralTextEditCLI won't ask for a program, but read it from that file.  E.g. running with `--program prog.ptep`, the user is only prompted for the input

• New optional path parameter `input` added to CLI. If present proceduralTextEditCLI won't ask for the input, but read it from that file. E.g. running with `--input test.txt`, the user is only prompted for the program
• New optional path parameter `output` added to CLI. If present proceduralTextEditCLI won't print the result, but write it to that file
  All three parameters can be combined. proceduralTextEditCLI then only operates on files.
  E.g. `proceduralTextEditCLI --input test.txt --program prog.ptep --output result.txt`
• More detailed explanation of CLI version in README