change generator/ filenames to match classenames

also clear some header dependedcies.
we use boost::scoped_ptr instead if util::scoped_ptr in create_engine
because msvc gives warning when util::scoped_ptr is used with incomplete
types due to its virtual destructor.
refactor cave map generator

we now use a helper class to store the temporary variables for
create_scenario so that we dont have to carry them areoudn if we aren't
exacuting  create_scenario
don't calculate flipx in cavegen constructor

just like the other parts of the generation this should take place in
create_scenario
add default implementtion for map_generator::user_config
allow to pass a randomseed to cave_map_generator_job

it's not used yet, the plan is to allow passing a randomseed to all
map_generator::generate_map/scenario
fix \  -> / in filepath
Merge pull request #279 from gfgtdf/map_generator_refactor

Map generator refactor

the intentions/plans are:
1) fix the 'single use' cave map generator to work in mp.
we fix this by splitting the cave_map_generator into 
cave_map_generator and cave_map_generator_job from which the later is a temporary object used during generate_scenario/map

2) allow to pass a (platform independent) seed to all map generators, this is not completely implemented yet. I implemented this for the cave_map_generator_job and it was already implemented for the yamg. Is still needs to be implemented for the default_map_generator