Add PC to QEMU's read / write callbacks

[rmalmain]

qemu does not update the cpu's pc at the middle of a translation block.
2 things we could have done:

• update pc before calling the callbacks (arch dependent)
• give the correct pc as argument (arch independent, but fetch or updating pc through Qemu::read_reg or Qemu::write_reg will not work as expected)

also, adds a logging module to log events in qemu