Functional component changes requested

[ghost]

Couple of things:

• [x] Need Doxygen documentation enabled for functional components
• [x] (might) Need ArchData::Line objects to be able to copy to each other and clear dirty flags
• [x] Speed up the Register class' masked paths -- uses BitVector which is very slow.
• [ ] Add set/get methods that will set/get bits in a given register scratch based on fields, but won't update the register:

  auto reg = regset->getRegister("FPSCR");
  auto reg_val = reg->read<uint32_t>();
  reg->set(reg_val, "FEX", 0);
  reg->set(reg_val, "FR",  0);
  reg->set(reg_val, "RN",  0x3);
  sparta_assert(reg->get(reg_val, "RN") == 0x3);
  reg->write(reg_val);

[klingaard]

@cnyce is looking at revamping this a bit.