FindAdv: Optimization

FindAdv: Optimization

Using unordered_map instead of map.
Reasons:
1.) The relevant maps contain 166(Keys) and 649(Accents) entries.
  This mean that average access with 'map' needs 8 to 10 compares to find the value.
2.) Since we are using at least c++11, the unordered_map is available
2.) increasing the maps (in future) needs not to be considered anymore, because
  the access-time will not increase.