Enable running automated tests against FPGA target

[jbush001]

Currently, many automated tests are able to automatically run against either the emulator or the hardware model. It would be nice to add another target to test against hardware (FPGA). This could send the test program over the serial port and read the response on the console via the serial_boot command.

• There's no way to remotely reset the board currently.
• Serial_boot never exits once it goes into console mode. Could modify to have another mode.

[jbush001]

A few ideas:

• Related to issue #71, could have the mechanism that halts the test perform a reboot of the processor. This would require the register to connect to the reset line. If a test hung, it couldn't be recovered, but in the passing case, the device would be ready to load the next test.
• Have serial boot exit when it receives ^D character in terminal.

[jbush001]

Next steps:

• Create a module that uses virtual JTAG and can reset the processor (this can be ORed with the hardware button)
• Add support to test harness to invoke Altera tools to reset board with virtual JTAG
• Make serial_loader exit console mode when it receives ^D
• Modify standard library to send a ^D out the serial port when it exits.

[jbush001]

This is now functional, but requires manually pressing the reset button every time. Need to hook up virtual JTAG reset.

[jbush001]

Last change should support resetting board automatically using virtual JTAG, but it doesn't work yet. Need to debug.