polarization etc.

before init()

Add +=, etc operators in PhysicsType

NOT be set via configure of DVCSProcessModule as this changes the
behaviour for ALL observables, and I need to change it only in
particular cases (e.g. for COMPASS cross-sections that will be released
with the subtracted BH (uuuu, so exited!)). I changed DVCSProcessModule
to select the process in an safe way. I added
DVCSCrossSectionUUBHSubProc module, which return BH cross section only
and can be used as a demonstartion of the usage of this modification.
#27 

(WIP, to be tested)

update setting of ScalesModule and XiConverterModule in ProcessModule
#31

Remove unused models #27
Propagate configure in all observables #26 #25
WIP

With this commit all modules are renamed to the proposed scheme. Some
work is still needed to propagate the changes (documentation and other
projects)

Issues found during the commenting have been summarized in #15
Files that most probably will not enter v1 have been marked in
wiki:Doxygen #5
Add namespace to PhysConst. #14
Correct top charge squared in PhysConst.
Add top to PartonContent

In PARTONS:
- add beam energy member to ObservableKinematics
- remove setting of beam energy via Process 
- update ObservableKinematics DAO and mySQL scheme

In PARTONS :
- Implement new feature : CrossConfiguration ; Now it is possible to configure all modules and submodules at each level of computation ; Care !!! now developers need to handle correctly life cycle of objects because they are now created and destroyed in module implementation.
- Update XMLSchema to handle CrossConfiguration feature by automation.
- In List add some stuff for CrossConfiguration feature.
- Implement new BaseObjectData class to hold modules and sub-modules configuration and their parameters ; Needed for CrossConfiguration feature.
- Update as a draft Task class to handle previous BaseObjectData ; Needed for CrossConfuguration feature.
- In all classes replace std::runtime_error by CustomException and add missing throw keyword.
- In all abstract classes (or class that is module dependent) add new prepareSubModule(...) to handle CrossConfiguration feature.
- Update Fourier observables to remove pointers memory problems ; Now Fourier observables inherit from their Phi dependent observable ; Remove FourierObservable class.
- Update as a draft DefaultXMLParser and XMLParserI to handle CrossConfiguration feature.
- And other stuff that I forgot ...