Formatter config

[cal101]

Dear Raquel!

I am sorry for the formatter obstacles. I tried to translate the formatting config I am familiar with from the gradle formatter to a maven formatter I was not familiar with and I was not good enough.

This pull requests takes a totally different approach: Maven calls out to gradle via plugin to execute the gradle plugin "spotless" that does the formatting and also removes unused imports. This uses the formatting utils I am familiar with but does not need a gradle installation or migration.

The changes compared to the previous configuration: see https://github.com/cal101/javalang-compiler/commit/b5be5fd8a5c679e23599c680e811f1c55ebf7c2d

Execute the formatter via

mvn org.fortasoft:gradle-maven-plugin:invoke

The result can also be see here: https://github.com/cal101/javalang-compiler/commit/240eda04a0bb6e90bbc0cd4d3d90a9680f00aecc

• A lot of trailing whitespace and blank lines before a block ends are now properly removed.
• Only a few import lines are changed. That means the import order config matches most of the code.

To see the real differences it's best to call the formatter in your own workspace and apply it and then compare with "git diff -w" to ignore whitespace.

I hope this helps.

Cal

[cal101]

Some fine tuning and fixing of import order config done.