Resolve "Make grammar(s) more concise"

- rename intermediate grammar and aspect files
- updated documentation
- reorder attributes for generation to match mustache files and types
- update build.gradle's, use java11 and "our" jastadd-fork for testing
- set experimental-options for suspicious test singleVariantIncremental, but disabled because it fails indeterministically
- print YAML generation only if verbose
- auto-format aspect files
- some refactorings for #39
- unified handler setup
- run negative test cases also in CI
- move generateAspect into Compiler.java
- navigation partly generated using abstract-type-navigation-pp