Hooks added for (I hope) the final and complete set of all parameter-changing
M Codes that we will need.  Network initialisation delayed until after the
config.g file is run, to allow machine name etc to be set from that.
Temperature range checking added (see Configuration.h).  If temps repeatedly
fall outside the set range, it assumes the thermistor is bust and turns off the heater.
All responses to GCodes routed through a single function in the class GCodes
to allow the firmware to emulate how other firmware (e.g. Marlin) responds.  Emulation not yet implemented, but should now be easy.
Added cooling fan control.
Axis angle compensation code added.  Briefly tested in XY plane.  Seems to work.  More testing is probably needed...
Memory diagnostics added.  Mem usage is printed whenever you turn debugging on (even if it is already on).
Fixed Timer overflow bug.
Marlin emulation implemented.  Pretty much working, but not extensively tested.
File printing in Marlin emulation w. Pronterface fixed.
Ability to specify bed Z probe points added.  See M505.
Added user-selection of IP address via M502.
Shifted new M codes to start at M550.  Added setting of Netmask and gateway.
GCode file upload via USB working.
File upload mechanism also now works with the web code.  If we can open a user's GCode file in the Javascript this will allow web uploads.  Horay!  See: http://www.html5rocks.com/en/tutorials/file/dndfiles/
Line-by-line web file upload added, but causes troub by blitzing http requests; so commented out.  Unused pages for first release removed.
Added z-probe type selection.  See M558.
M503 implemented.  Prints the config file to USB.
M503 implemented (tis time with added bug-free-ness...)
Removed tiny buggette in the heat timing code.
Upload of configuration file config.g implemented with M559.