File headers connected to student work of @frey_m

This is a list of issues that add a file header according to #482 (closed) to all classes that are developed during the various theses of @frey_m:

• AMR particle classes (see !317 (merged) and !318 (merged))
• Sampler (see !316 (merged))
• DataSink writer classes (see !315 (merged))
• Trim coil classes (see !320 (merged))
• semester thesis (matched distribution) (see !319 (merged))
• Optimiser expressions (see !321 (merged))
• Strongly modified classes (e.g. PartBunchBase and RK4) Edit: Further discussed in #482 (closed).