Merge fixes added to master into experimental

Complete rewrite of time estimation with acceleration

Fixed documentation regarding wxPython on MacOS Lion

changed instruction for MacOs Lion to download stable wxPython because unstable version breaks the axis control panel

Bugfix: paths were not hilighted in preview during print anymore

Faster firmware startup for sanguinololu and similar boards

Made SD Upload call the right function - not the SD Print function

Fix manually input port names

port setting is now also respected if the port exists but is not detected in scan (for udev symlinks)

  Accounts for G4 Pxxx
  Accounts for Z moves as well.
  Also prints out duration for each layer while calculating the total time.

  Does not use individual axis acceleration, only uses sprinter default acceleration 1500.0 mm/s/s
  Does not count E for timing... so if E is slowing down the move, we're not accounting for that.

** fixed: 2x distance to reach full speed, because accel and decel to 0.0 at each move.

TODO:
  Get Device Caps (per axis acceleration, per axis speed limits)
  anything else...?

Fix send box not expanding correctly, and fix layouting in custom button dialog

Sends M21 whenever SD Upload or SD Print are used.

Automatically attempts to initialise the SD card whenever either of the SD
card related buttons are used.

Allow the graph to expand

This cleans up the layouting code for the GUI

Added Current Z-Height to the status message.

Also added "Print Began at: HH:MM:SS"
and added the message "Print Ended at: HH:MM:SS: and took...

Improved status line estimated time remaining.

Fixed the time estimator in pronsole.py