Particle generation breaks restart feature

[FabienPean-Virtonomy]

https://github.com/Xiangyu-Hu/SPHinXsys/blob/e5d224d7af1d0685165e45224ecc50d65186f5cc/SPHINXsys/src/shared/bodies/base_body.h#L137-L144

Restart is inherently broken with new particle generation approach. For any particle generator, initializeOtherVariables happens after the function implemented by the user, the initialization of extra variable based on a function such as

https://github.com/Xiangyu-Hu/SPHinXsys/blob/e5d224d7af1d0685165e45224ecc50d65186f5cc/SPHINXsys/src/shared/particles/solid_particles.cpp#L30-L32

is (1) crashing if the variable was registered by the user inadvertently (avoidable and ok, requires removing some lines), and (2) overriding any user/file loaded values (more problematic from design POV). See the sources of problems in base_particles.hpp

https://github.com/Xiangyu-Hu/SPHinXsys/blob/e5d224d7af1d0685165e45224ecc50d65186f5cc/SPHINXsys/src/shared/particles/base_particles.hpp#L45-L56

and

https://github.com/Xiangyu-Hu/SPHinXsys/blob/e5d224d7af1d0685165e45224ecc50d65186f5cc/SPHINXsys/src/shared/particles/base_particles.hpp#L59-L71

[Xiangyu-Hu]

Yes. This issue is very relevant to that a variable is only allowed once. The other Variable are only those in particle classes. Any new variable will be defined in method will be initialized in the specific method class. My original design is separate geometric model variable, physical model variables and dynamics relevant variables. The first two are defined in particles, the third in method classes. However, the clear separation between the three is not very obvious.