Enforce constness/read-only access of specification through the code base

[davidgraeff]

• Fixes a double free memory corruption. Fixes #163
• All DSO sub-models (e.g. DSO-5000, DSO-5000A) directly inherit from DsoModel.
• Remove DataArray util class. std::vector will perfectly do it and has the same memory allocation with common lib-std implementations (gcc, clang, VS).
• Make all short forwarding methods of USBDevice inline.
• Move BulkCommand+ControlCommand to hantekprotocol.
• Move usbprinterror method to USBDevice file.