Put back build directory into repository

Add build directory with dummy .gitignore
Fix compilation error

Comment unused variable
Cleanup dFunction.hpp

Fix white-space errors, add _debug flag, remove some obsolete lines.
Add missing function to set _debug flag to dFunctionCached

Add member function
Cleanup factorial.hpp

Add _debug flag, improve debug output, fix whitespace errors.
Fix white-space errors

sic!
Fix compilation error in factorial.hpp

Add std:: were needed
Add accessor for debug flag to dFunction, factorial and spinUtils

sic!
Some cleanup in particle class

Rename some accessors and member variables; fix white-space errors
Some cleanup in decayTopology

sic!
Rename some vertex accessors

sic!
Some cosmetical changes to vertex classes

sic!
Some cosmetic changes mainly to isobarDecayVertex

sic!
Merge pull request #1 from bgrube/cuda

Cuda