rewritten intro paragraphs of reflection overview

* removed terminological issues
* removed the fact that Java reflection is only that; dynamic proxies
  and APT are other parts of the Java reflection API -- runtime behavioral
  reflection (DP) and compile-time reflection (APT)
* removed the paradigm status-quo stuff, since that doesn't do justice
  to the actual state of things, especially for OOP
  (eg. Smalltalk, Python, Ruby), and FP (macros in Scheme/Racket).
Merge pull request #234 from xeno-by/topic/reflection

rewritten intro paragraphs of reflection overview