Fix #283, accel calibration getting stuck/out of sync

Added in functionality for a countdown timer to let users know how long
they have left to continue the calibration procedure. Once it times out,
APM will automatically move on to the next step, and "continue" will need
to be clicked continuously to cancel out. Ardupilot pull req #1003
addresses this. This fix also adds in new LinkInteface functionality,
enableTimeouts() and disableTimeouts() to enable/disable auto-resetting of
APM on communications silence.
Removed a commenting out that accidently got commited
Configuration: Allow custom data rates
Linux: Changed busy-serial-port error message to reference modemmanager
Linux Packaging: better compatibility with .deb standard
Advanced Param List: Fixes #153 Add ranges/defaults for params to view
MAVLink: Fixes #310 tlogs to be compatible with MP/MAVProxy
Terminal View: Fixes Terminal to not show the MAVLink connect button

Fix up Terminal View so it disables the connect button in terminal if connected to an active MAV to make it more clear that you need to connect below.
Also fixed the issue of not remember the last save port.
MAVLink: removed accidentally added member variable
Graph: updated to QCustomPlot 1.2.1
Graph: Now saving 'M' fields as strings.
Graph: Added 'Mode' to be plot table, added vertical drag/zoom

Still has a few bugs, but shows potential...
Graph: removed unused SLOT connection.