Replace 9 seperate valueChanged() signals with just 1, and remove the resultant tons of code duplication

Further consolidation of Plot code into ChartPlot. Also removed some unused variables from LinechartWidget.cc. Also only active curves are recolored in the IncrementalPlot class.

Modified the Linechart widget so that the "Show units" button is under the "Curve Selection" frame, which is what it actually modifies.
Also moved all of the UI that was under the "Curve Selection" to inside of it at the bottom so that the grouping of UI elements is more coherent.

Removed some dead code.
Added more valueChanged() signals to account for every data type. This moves the conversion over into the valueChanged receivers, which while it will require more slot-functions, makes it easier to add more code as any necessary conversion is done internally to the slot and so the signaler doesn't need to know the details.
I also added some more details on the types of units expected by valueChanged().

Added not yet working version of logging / log replay, fixed ALL bugs in main window, enabled full persistence in main window and serial link.

Improved line chart, brought back movement on HUD (but still looks somewhat wrong on the dials). Fixed logging for ground time mode

Added new options for windows serial port, fixed a number of bugs, added customizing options to instrument widgets

Substantially bugfixed and improved deactivation/activation and persistence of widgets. A lot of testing of Google Earth view, only minor improvements

Fixed initial startup bugs, cleaned up the activation-deactivation of update timers. Added initial instructions for new users.

Significantly improved plotting, now capturing data in linechart allows limmediate processing / analysis of the whole flight

Improved runtime performance, currently hunting down a bug where the whole application gets repainted although only parts of it are refreshed