Added some argument checking

Added range check to guard
DVRPTRVersion now also implements IComparable (non-generic)
Added CompareHelper to allow easy comparison of reference types
Added some argument checking

Added range check to guard
DVRPTRVersion now also implements IComparable (non-generic)
Added CompareHelper to allow easy comparison of reference types
Removed useless static method, added some comment
imrovement and refactoring start

Improved IsOpen
Started refactoring
Refactoring splitting PCP2 from command logic stage 1

See https://github.com/F4FXL/OpenCC/issues/1
Refactoring splitting PCP2 from command logic stage 2

See https://github.com/F4FXL/OpenCC/issues/1
Merge branch 'master' of https://github.com/F4FXL/OpenCC