move LogicalPart from LogicalPartsManager.rb to LogicalPart.rb
add TestLogicalPart.rb and TestLogicalPartsManager.rb
move PosPart from PosPartsManager.rb to PosPart.rb
add TestPosPartsManager.rb and TestPosPart.rb
add BasicSolidDefiner
add CompoundSolidDefiner
use  instead of p
add an argument to initialize()
add UnknownSolidDefiner
add a check if the partName is known
use a known solid name for tests
remove all sub classes of Solid
add class SolidDefiner
move SolidDefiner, UnknownSolidDefiner, BasicSolidDefiner, CompoundSolidDefiner to SolidDefiner.rb from Solid.rb