Replace Abstract<whatever> classes with proper* interfaces.

(*) C++ does not have proper interfaces ;)

 - Make interfaces interfaces - remove member variables from them
 - Remove redundant interfaces
 - Remove redundant classes aka StateNonTerminalMap. This functionality can be achieved by simpler std::map
 - Ensure second call of convert() will not fail by creating everything on fly. Thompson is the only algorithm where output must be member variable to make things simple. C11 will hopefully resolve this.
 - Hexavigesimal for Brzozowski classes.

 - rewrite follow function according to http://www.sciencedirect.com/science/article/pii/S030439759700296X, which makes a bit clearer what is going on inside
 - rename some foos and update doxygen

 - Removal of libaregexptree/RegExpAlphabet
 - Method getting regexp alphabet moved to alib/RegExp, alib/RegExpElement
 - Method getting get symbols list in order moved to aconversion/GlushkovTraversal as Glushkov algorithm is the only one using it
 - Reflect changes throughout project

 - RE to FA: comments
 - RE to RRG: fix generating epsilon rules and workaround for issue #22

Copy whole source object into class, we have no control over its lifetime.