Add the attributes for profession and unit_labor, and (re)name the
protobuf messages JobSkillAttr, ProfessionAttr, and UnitLaborAttr to
better reflect their content and distinguish them from e.g. the
SkillInfo message included in BasicUnitInfo.
I expect the majority of methods will have to suspend the core
first thing anyway, so this will reduce typing and bugs.
Also get rid of the "me->" ugliness by splitting threadFn.