Modularisation

[Devetak]

Creates macros for 'inheritance' making the creation of custom types simpler. The macro is to be used inside a struct to ensure all the necessary fields are present in the struct. Like

struct Worker <: AbstractWorker
      @worker
      new_property
end

by default all the entries are either Float64, Int or vectors of them as appropriate. One can specify other types by passing values to the macro.

[AldoGl]

Excellent work @Devetak! I'll try to correct the error in the docs and then we can merge

[AldoGl]

rebasing and merging