Automate tasks like generation of derived sources i.e. in examples and run example related tests scripts

[jsinger67]

Was first mentioned in (#31 (comment))

[jsinger67]

All common tasks that are used could be defined using this approach.

• Format and build
• Build and test
• Build and run examples as special test scenario
• Applying version labels
• etc.

[ryo33]

cargo make is a very useful tool, but I think there are only a few projects that need it.
Cargo is already a powerful tool for most projects.

I used it for a personal project and had the following problems.

• cargo install cargo-make is slow (it makes CI slow)
• things are getting more and more complex

Then, I switch to cargo and a few portable shell scripts for CI. If we develop on Windows, we need a bash-compatible shell or WSL.

[jsinger67]

I wasn't aware of the performance problems of cargo make. Fortunately I spent no effort for this issue yet.
I will rethink the problem and find another solution.
Some things (mostly Powershell scripts that run examples) can be solved by using the built-in test infrastructure. Others (mostly generation of parser code) can be achieved by portable scripts or some kind of build steps using build.rs.

[jsinger67]

Fixed with 82fb6f4
Automation with cargo-make is an add-on. You don't need to use it in regular development.
It is rather a way to automate special tasks like building example sources to check if parol generates different output.

If you want to use it you need to install cargo make:

  ```shell
  cargo install cargo-make
  ```

Then you can invoke the example source generation with this command

  ```shell
  cargo make generate_examples
  ```

The other use case "Running the generated parsers against special input files" was integrated into a a new integration test.