Support providing `DiagnosticListener` for compiling

[Marcono1234]

Resolves #93

Adds a new CachedCompiler#loadFromJava overload with javax.tools.DiagnosticListener parameter. The behavior of the existing loadFromJava methods remains the same.

Also adds Javadoc to some of the methods and constructors. Edit: Sorry I overlooked that there is already #140 for adding Javadoc. Feel free to merge that first and then I can try to resolve conflicts here and maybe make some small Javadoc adjustments.

Any feedback is appreciated!