Review lemon/maps.h

[Alpar Juttner]

We must clean up this file for Lemon 1.0. For this we should

• classify the tools into this catergories
  • frequently used
  • sometimes used
  • hardly used
  • never
• remove those having unclear purposes or little use.
• think over which ones can be merged together without a big loss in their functionality
• try to find smart name for all the tools that survive this process
• revised the documentations, as well.